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Vilela J, Rasga C, Santos JX, Martiniano H, Marques AR, Oliveira G, Vicente AM. Bridging Genetic Insights with Neuroimaging in Autism Spectrum Disorder-A Systematic Review. Int J Mol Sci 2024; 25:4938. [PMID: 38732157 PMCID: PMC11084239 DOI: 10.3390/ijms25094938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/22/2024] [Accepted: 04/25/2024] [Indexed: 05/13/2024] Open
Abstract
Autism Spectrum Disorder (ASD) is an early onset neurodevelopmental disorder characterized by impaired social interaction and communication, and repetitive patterns of behavior. Family studies show that ASD is highly heritable, and hundreds of genes have previously been implicated in the disorder; however, the etiology is still not fully clear. Brain imaging and electroencephalography (EEG) are key techniques that study alterations in brain structure and function. Combined with genetic analysis, these techniques have the potential to help in the clarification of the neurobiological mechanisms contributing to ASD and help in defining novel therapeutic targets. To further understand what is known today regarding the impact of genetic variants in the brain alterations observed in individuals with ASD, a systematic review was carried out using Pubmed and EBSCO databases and following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. This review shows that specific genetic variants and altered patterns of gene expression in individuals with ASD may have an effect on brain circuits associated with face processing and social cognition, and contribute to excitation-inhibition imbalances and to anomalies in brain volumes.
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Affiliation(s)
- Joana Vilela
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (J.V.); (C.R.); (J.X.S.); (H.M.); (A.R.M.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Célia Rasga
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (J.V.); (C.R.); (J.X.S.); (H.M.); (A.R.M.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - João Xavier Santos
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (J.V.); (C.R.); (J.X.S.); (H.M.); (A.R.M.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Hugo Martiniano
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (J.V.); (C.R.); (J.X.S.); (H.M.); (A.R.M.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Ana Rita Marques
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (J.V.); (C.R.); (J.X.S.); (H.M.); (A.R.M.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Guiomar Oliveira
- Unidade de Neurodesenvolvimento e Autismo, Serviço do Centro de Desenvolvimento da Criança, Centro de Investigação e Formação Clínica, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-602 Coimbra, Portugal;
- Coimbra Institute for Biomedical Imaging and Translational Research, University Clinic of Pediatrics, Faculty of Medicine, University of Coimbra, 3000-602 Coimbra, Portugal
| | - Astrid Moura Vicente
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (J.V.); (C.R.); (J.X.S.); (H.M.); (A.R.M.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
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Mosconi MW, Stevens CJ, Unruh KE, Shafer R, Elison JT. Endophenotype trait domains for advancing gene discovery in autism spectrum disorder. J Neurodev Disord 2023; 15:41. [PMID: 37993779 PMCID: PMC10664534 DOI: 10.1186/s11689-023-09511-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 11/09/2023] [Indexed: 11/24/2023] Open
Abstract
Autism spectrum disorder (ASD) is associated with a diverse range of etiological processes, including both genetic and non-genetic causes. For a plurality of individuals with ASD, it is likely that the primary causes involve multiple common inherited variants that individually account for only small levels of variation in phenotypic outcomes. This genetic landscape creates a major challenge for detecting small but important pathogenic effects associated with ASD. To address similar challenges, separate fields of medicine have identified endophenotypes, or discrete, quantitative traits that reflect genetic likelihood for a particular clinical condition and leveraged the study of these traits to map polygenic mechanisms and advance more personalized therapeutic strategies for complex diseases. Endophenotypes represent a distinct class of biomarkers useful for understanding genetic contributions to psychiatric and developmental disorders because they are embedded within the causal chain between genotype and clinical phenotype, and they are more proximal to the action of the gene(s) than behavioral traits. Despite their demonstrated power for guiding new understanding of complex genetic structures of clinical conditions, few endophenotypes associated with ASD have been identified and integrated into family genetic studies. In this review, we argue that advancing knowledge of the complex pathogenic processes that contribute to ASD can be accelerated by refocusing attention toward identifying endophenotypic traits reflective of inherited mechanisms. This pivot requires renewed emphasis on study designs with measurement of familial co-variation including infant sibling studies, family trio and quad designs, and analysis of monozygotic and dizygotic twin concordance for select trait dimensions. We also emphasize that clarification of endophenotypic traits necessarily will involve integration of transdiagnostic approaches as candidate traits likely reflect liability for multiple clinical conditions and often are agnostic to diagnostic boundaries. Multiple candidate endophenotypes associated with ASD likelihood are described, and we propose a new focus on the analysis of "endophenotype trait domains" (ETDs), or traits measured across multiple levels (e.g., molecular, cellular, neural system, neuropsychological) along the causal pathway from genes to behavior. To inform our central argument for research efforts toward ETD discovery, we first provide a brief review of the concept of endophenotypes and their application to psychiatry. Next, we highlight key criteria for determining the value of candidate endophenotypes, including unique considerations for the study of ASD. Descriptions of different study designs for assessing endophenotypes in ASD research then are offered, including analysis of how select patterns of results may help prioritize candidate traits in future research. We also present multiple candidate ETDs that collectively cover a breadth of clinical phenomena associated with ASD, including social, language/communication, cognitive control, and sensorimotor processes. These ETDs are described because they represent promising targets for gene discovery related to clinical autistic traits, and they serve as models for analysis of separate candidate domains that may inform understanding of inherited etiological processes associated with ASD as well as overlapping neurodevelopmental disorders.
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Affiliation(s)
- Matthew W Mosconi
- Schiefelbusch Institute for Life Span Studies and Kansas Center for Autism Research and Training (K-CART), University of Kansas, Lawrence, KS, USA.
- Clinical Child Psychology Program, University of Kansas, Lawrence, KS, USA.
| | - Cassandra J Stevens
- Schiefelbusch Institute for Life Span Studies and Kansas Center for Autism Research and Training (K-CART), University of Kansas, Lawrence, KS, USA
- Clinical Child Psychology Program, University of Kansas, Lawrence, KS, USA
| | - Kathryn E Unruh
- Schiefelbusch Institute for Life Span Studies and Kansas Center for Autism Research and Training (K-CART), University of Kansas, Lawrence, KS, USA
| | - Robin Shafer
- Schiefelbusch Institute for Life Span Studies and Kansas Center for Autism Research and Training (K-CART), University of Kansas, Lawrence, KS, USA
| | - Jed T Elison
- Institute of Child Development, University of Minnesota, Minneapolis, MN, USA
- Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA
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Pretzsch CM, Ecker C. Structural neuroimaging phenotypes and associated molecular and genomic underpinnings in autism: a review. Front Neurosci 2023; 17:1172779. [PMID: 37457001 PMCID: PMC10347684 DOI: 10.3389/fnins.2023.1172779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 06/09/2023] [Indexed: 07/18/2023] Open
Abstract
Autism has been associated with differences in the developmental trajectories of multiple neuroanatomical features, including cortical thickness, surface area, cortical volume, measures of gyrification, and the gray-white matter tissue contrast. These neuroimaging features have been proposed as intermediate phenotypes on the gradient from genomic variation to behavioral symptoms. Hence, examining what these proxy markers represent, i.e., disentangling their associated molecular and genomic underpinnings, could provide crucial insights into the etiology and pathophysiology of autism. In line with this, an increasing number of studies are exploring the association between neuroanatomical, cellular/molecular, and (epi)genetic variation in autism, both indirectly and directly in vivo and across age. In this review, we aim to summarize the existing literature in autism (and neurotypicals) to chart a putative pathway from (i) imaging-derived neuroanatomical cortical phenotypes to (ii) underlying (neuropathological) biological processes, and (iii) associated genomic variation.
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Affiliation(s)
- Charlotte M. Pretzsch
- Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, United Kingdom
| | - Christine Ecker
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
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Beopoulos A, Géa M, Fasano A, Iris F. Autism spectrum disorders pathogenesis: Toward a comprehensive model based on neuroanatomic and neurodevelopment considerations. Front Neurosci 2022; 16:988735. [PMID: 36408388 PMCID: PMC9671112 DOI: 10.3389/fnins.2022.988735] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 10/10/2022] [Indexed: 11/26/2023] Open
Abstract
Autism spectrum disorder (ASD) involves alterations in neural connectivity affecting cortical network organization and excitation to inhibition ratio. It is characterized by an early increase in brain volume mediated by abnormal cortical overgrowth patterns and by increases in size, spine density, and neuron population in the amygdala and surrounding nuclei. Neuronal expansion is followed by a rapid decline from adolescence to middle age. Since no known neurobiological mechanism in human postnatal life is capable of generating large excesses of frontocortical neurons, this likely occurs due to a dysregulation of layer formation and layer-specific neuronal migration during key early stages of prenatal cerebral cortex development. This leads to the dysregulation of post-natal synaptic pruning and results in a huge variety of forms and degrees of signal-over-noise discrimination losses, accounting for ASD clinical heterogeneities, including autonomic nervous system abnormalities and comorbidities. We postulate that sudden changes in environmental conditions linked to serotonin/kynurenine supply to the developing fetus, throughout the critical GW7 - GW20 (Gestational Week) developmental window, are likely to promote ASD pathogenesis during fetal brain development. This appears to be driven by discrete alterations in differentiation and patterning mechanisms arising from in utero RNA editing, favoring vulnerability outcomes over plasticity outcomes. This paper attempts to provide a comprehensive model of the pathogenesis and progression of ASD neurodevelopmental disorders.
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Affiliation(s)
| | | | - Alessio Fasano
- Division of Pediatric Gastroenterology and Nutrition, Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, United States
- Division of Pediatric Gastroenterology and Nutrition, Center for Celiac Research and Treatment, Massachusetts General Hospital for Children, Boston, MA, United States
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Comparan-Meza M, Vargas de la Cruz I, Jauregui-Huerta F, Gonzalez-Castañeda RE, Gonzalez-Perez O, Galvez-Contreras AY. Biopsychological correlates of repetitive and restricted behaviors in autism spectrum disorders. Brain Behav 2021; 11:e2341. [PMID: 34472728 PMCID: PMC8553330 DOI: 10.1002/brb3.2341] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/31/2021] [Accepted: 08/10/2021] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Autism Spectrum Disorder (ASD) is considered a neurodevelopmental condition that is characterized by alterations in social interaction and communication, as well as patterns of restrictive and repetitive behaviors (RRBs). RRBs are defined as broad behaviors that comprise stereotypies, insistence on sameness, and attachment to objects or routines. RRBs can be divided into lower-level behaviors (motor, sensory, and object-manipulation behaviors) and higher-level behaviors (restrictive interests, insistence on sameness, and repetitive language). According to the DSM-5, the grade of severity in ASD partially depends on the frequency of RRBs and their consequences for disrupting the life of patients, affecting their adaptive skills, and increasing the need for parental support. METHODS We conducted a systematic review to examine the biopsychological correlates of the symptomatic domains of RRBs according to the type of RRBs (lower- or higher-level). We searched for articles from the National Library of Medicine (PubMed) using the terms: autism spectrum disorders, ASD, and autism-related to executive functions, inhibitory control, inflexibility, cognitive flexibility, hyper or hypo connectivity, and behavioral approaches. For describing the pathophysiological mechanism of ASD, we also included animal models and followed PRISMA guidelines. RESULTS One hundred and thirty-one articles were analyzed to explain the etiology, continuance, and clinical evolution of these behaviors observed in ASD patients throughout life. CONCLUSIONS Biopsychological correlates involved in the origin of RRBs include alterations in a) neurotransmission system, b) brain volume, c) inadequate levels of growth factors, d) hypo- or hyper-neural connectivity, e) impairments in behavioral inhibition, cognitive flexibility, and monitoring and f) non-stimulating environments. Understanding these lower- and higher-level of RRBs can help professionals to improve or design novel therapeutic strategies.
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Affiliation(s)
- Miguel Comparan-Meza
- Maestría en Neuropsicología, Departamento de Neurociencias, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara, JAL, Mexico
| | - Ivette Vargas de la Cruz
- Unidad de Atención en Neurociencias, Departamento de Neurociencias, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara, JAL, Mexico
| | - Fernando Jauregui-Huerta
- Laboratorio de Microscopia de Alta Resolución, Departamento de Neurociencias, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara, JAL, Mexico
| | - Rocio E Gonzalez-Castañeda
- Laboratorio de Microscopia de Alta Resolución, Departamento de Neurociencias, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara, JAL, Mexico
| | - Oscar Gonzalez-Perez
- Laboratorio de Neurociencias, Facultad de Psicología, Universidad de Colima, Colima, COL, Mexico
| | - Alma Y Galvez-Contreras
- Unidad de Atención en Neurociencias, Departamento de Neurociencias, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara, JAL, Mexico
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Hashem S, Nisar S, Bhat AA, Yadav SK, Azeem MW, Bagga P, Fakhro K, Reddy R, Frenneaux MP, Haris M. Genetics of structural and functional brain changes in autism spectrum disorder. Transl Psychiatry 2020; 10:229. [PMID: 32661244 PMCID: PMC7359361 DOI: 10.1038/s41398-020-00921-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/05/2020] [Accepted: 06/09/2020] [Indexed: 12/21/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurological and developmental disorder characterized by social impairment and restricted interactive and communicative behaviors. It may occur as an isolated disorder or in the context of other neurological, psychiatric, developmental, and genetic disorders. Due to rapid developments in genomics and imaging technologies, imaging genetics studies of ASD have evolved in the last few years. Increased risk for ASD diagnosis is found to be related to many specific single-nucleotide polymorphisms, and the study of genetic mechanisms and noninvasive imaging has opened various approaches that can help diagnose ASD at the nascent level. Identifying risk genes related to structural and functional changes in the brain of ASD patients provide a better understanding of the disease's neuropsychiatry and can help identify targets for therapeutic intervention that could be useful for the clinical management of ASD patients.
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Affiliation(s)
- Sheema Hashem
- Functional and Molecular Imaging Laboratory, Sidra Medicine, Doha, Qatar
| | - Sabah Nisar
- Functional and Molecular Imaging Laboratory, Sidra Medicine, Doha, Qatar
| | - Ajaz A Bhat
- Functional and Molecular Imaging Laboratory, Sidra Medicine, Doha, Qatar
| | | | | | - Puneet Bagga
- Center for Magnetic Resonance and Optical Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Khalid Fakhro
- Department of Human Genetics, Sidra Medicine, Doha, Qatar
- Department of Genetic Medicine, Weill Cornell Medical College, Doha, Qatar
| | - Ravinder Reddy
- Center for Magnetic Resonance and Optical Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | | | - Mohammad Haris
- Functional and Molecular Imaging Laboratory, Sidra Medicine, Doha, Qatar.
- Laboratory Animal Research Center, Qatar University, Doha, Qatar.
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Alolaby RR, Jiraanont P, Durbin-Johnson B, Jasoliya M, Tang HT, Hagerman R, Tassone F. Molecular Biomarkers Predictive of Sertraline Treatment Response in Young Children With Autism Spectrum Disorder. Front Genet 2020; 11:308. [PMID: 32346385 PMCID: PMC7174723 DOI: 10.3389/fgene.2020.00308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 03/16/2020] [Indexed: 11/29/2022] Open
Abstract
Sertraline is one among several selective serotonin reuptake inhibitors (SSRIs) that exhibited improvement of language development in Autism Spectrum Disorder (ASD); however, the molecular mechanism has not been elucidated. A double blind, randomized, 6-month, placebo-controlled, clinical trial of low-dose sertraline in children ages (3–6 years) with ASD was conducted at the UC Davis MIND Institute. It aimed at evaluating the efficacy and benefit with respect to early expressive language development and global clinical improvement. This study aimed to identify molecular biomarkers that might be key players in the serotonin pathway and might be predictive of a clinical response to sertraline. Fifty eight subjects with the diagnosis of ASD were randomized to sertraline or placebo. Eight subjects from the sertraline arm and five from the placebo arm discontinued from the study. Furthermore, four subjects did not have a successful blood draw. Hence, genotypes for 41 subjects (20 on placebo and 21 on sertraline) were determined for several genes involved in the serotonin pathway including the serotonin transporter-linked polymorphic region (5-HTTLPR), the tryptophan hydroxylase 2 (TPH2), and the Brain-Derived Neurotrophic Factor (BDNF). In addition, plasma levels of BDNF, Matrix metallopeptidase 9 (MMP-9) and a selected panel of cytokines were determined at baseline and post-treatment. Intent-to-treat analysis revealed several primary significant correlations between molecular changes and the Mullen Scales of Early Learning (MSEL) and Clinical Global Impression Scale – Improvement (CGI-I) of treatment and control groups but they were not significant after adjustment for multiple testing. Thus, sertraline showed no benefit for treatment of young children with ASD in language development or changes in molecular markers in this study. These results indicate that sertraline may not be beneficial for the treatment of children with ASD; however, further investigation of larger groups as well as longer term follow-up studies are warranted.
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Affiliation(s)
- Reem Rafik Alolaby
- College of Health Sciences, California Northstate University, Rancho Cordova, CA, United States
| | - Poonnada Jiraanont
- Faculty of Medicine, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand
| | - Blythe Durbin-Johnson
- Division of Biostatistics, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Mittal Jasoliya
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Hiu-Tung Tang
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Randi Hagerman
- MIND Institute, University of California Davis Medical Center, Davis, Davis, CA, United States.,Department of Pediatrics, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States.,MIND Institute, University of California Davis Medical Center, Davis, Davis, CA, United States
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Brandenburg C, Blatt GJ. Differential serotonin transporter (5-HTT) and 5-HT 2 receptor density in limbic and neocortical areas of adults and children with autism spectrum disorders: implications for selective serotonin reuptake inhibitor efficacy. J Neurochem 2019; 151:642-655. [PMID: 31325179 PMCID: PMC6900089 DOI: 10.1111/jnc.14832] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 06/17/2019] [Accepted: 07/12/2019] [Indexed: 12/25/2022]
Abstract
As selective serotonin reuptake inhibitors (SSRIs) are among the most commonly prescribed medications in autism, we aimed to determine whether targets for SSRIs are differentially affected in three cortical areas in children and adults with autism compared to neurotypical individuals. Utilizing a large cohort of postmortem brain tissue (n = 14–19 per group), saturation ligand binding assays were conducted on sections from the anterior cingulate cortex (ACC), posterior cingulate cortex, and fusiform gyrus (FG). Specific binding to the 5‐HT transporter (5‐HTT) as well as to 5‐HT2 and 1A receptors (5‐HT₂, 5‐HT1A) was quantified in superficial and deep layers of each region using the ligands [3H]‐citalopram (5‐HTT), [3H]‐ketanserin (5‐HT2), and [3H]‐8‐OH‐DPAT (5‐HT1A). A Welch’s t‐test was utilized to compare receptor densities (Bmax), revealing a statistically significant decrease in 5‐HTT within the ACC of the entire autism cohort. There was also a decrease in 5‐HT2 receptor density in the ACC in the adult cohort, but not in child postmortem autism cases as compared to controls. Comparing linear regression lines of Bmax values plotted against age, shows a significantly lower intercept for 5‐HTT in autism (p = 0.025). 5‐HT₂ density increases with age in control cases, whereas in autism there is a decrease with age and significantly different slopes between regression lines (p = 0.032). This suggests a deficit in 5‐HTT within the ACC in individuals with autism, while decreases in 5‐HT₂ density are age‐dependent. There were no differences in receptor densities in the posterior cingulate cortex or FG in autism and no differences in ligand affinity (KD) across all regions and ligands examined. ![]()
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Affiliation(s)
- Cheryl Brandenburg
- Program on Neuroscience, Hussman Institute for Autism, Baltimore, Maryland, USA
| | - Gene J Blatt
- Program on Neuroscience, Hussman Institute for Autism, Baltimore, Maryland, USA
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Klein M, van Donkelaar M, Verhoef E, Franke B. Imaging genetics in neurodevelopmental psychopathology. Am J Med Genet B Neuropsychiatr Genet 2017; 174:485-537. [PMID: 29984470 PMCID: PMC7170264 DOI: 10.1002/ajmg.b.32542] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 02/02/2017] [Accepted: 03/10/2017] [Indexed: 01/27/2023]
Abstract
Neurodevelopmental disorders are defined by highly heritable problems during development and brain growth. Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), and intellectual disability (ID) are frequent neurodevelopmental disorders, with common comorbidity among them. Imaging genetics studies on the role of disease-linked genetic variants on brain structure and function have been performed to unravel the etiology of these disorders. Here, we reviewed imaging genetics literature on these disorders attempting to understand the mechanisms of individual disorders and their clinical overlap. For ADHD and ASD, we selected replicated candidate genes implicated through common genetic variants. For ID, which is mainly caused by rare variants, we included genes for relatively frequent forms of ID occurring comorbid with ADHD or ASD. We reviewed case-control studies and studies of risk variants in healthy individuals. Imaging genetics studies for ADHD were retrieved for SLC6A3/DAT1, DRD2, DRD4, NOS1, and SLC6A4/5HTT. For ASD, studies on CNTNAP2, MET, OXTR, and SLC6A4/5HTT were found. For ID, we reviewed the genes FMR1, TSC1 and TSC2, NF1, and MECP2. Alterations in brain volume, activity, and connectivity were observed. Several findings were consistent across studies, implicating, for example, SLC6A4/5HTT in brain activation and functional connectivity related to emotion regulation. However, many studies had small sample sizes, and hypothesis-based, brain region-specific studies were common. Results from available studies confirm that imaging genetics can provide insight into the link between genes, disease-related behavior, and the brain. However, the field is still in its early stages, and conclusions about shared mechanisms cannot yet be drawn.
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Affiliation(s)
- Marieke Klein
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
| | - Marjolein van Donkelaar
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
| | - Ellen Verhoef
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
| | - Barbara Franke
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
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Muller CL, Anacker AMJ, Veenstra-VanderWeele J. The serotonin system in autism spectrum disorder: From biomarker to animal models. Neuroscience 2016; 321:24-41. [PMID: 26577932 PMCID: PMC4824539 DOI: 10.1016/j.neuroscience.2015.11.010] [Citation(s) in RCA: 308] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 10/26/2015] [Accepted: 11/04/2015] [Indexed: 02/02/2023]
Abstract
Elevated whole blood serotonin, or hyperserotonemia, was the first biomarker identified in autism spectrum disorder (ASD) and is present in more than 25% of affected children. The serotonin system is a logical candidate for involvement in ASD due to its pleiotropic role across multiple brain systems both dynamically and across development. Tantalizing clues connect this peripheral biomarker with changes in brain and behavior in ASD, but the contribution of the serotonin system to ASD pathophysiology remains incompletely understood. Studies of whole blood serotonin levels in ASD and in a large founder population indicate greater heritability than for the disorder itself and suggest an association with recurrence risk. Emerging data from both neuroimaging and postmortem samples also indicate changes in the brain serotonin system in ASD. Genetic linkage and association studies of both whole blood serotonin levels and of ASD risk point to the chromosomal region containing the serotonin transporter (SERT) gene in males but not in females. In ASD families with evidence of linkage to this region, multiple rare SERT amino acid variants lead to a convergent increase in serotonin uptake in cell models. A knock-in mouse model of one of these variants, SERT Gly56Ala, recapitulates the hyperserotonemia biomarker and shows increased brain serotonin clearance, increased serotonin receptor sensitivity, and altered social, communication, and repetitive behaviors. Data from other rodent models also suggest an important role for the serotonin system in social behavior, in cognitive flexibility, and in sensory development. Recent work indicates that reciprocal interactions between serotonin and other systems, such as oxytocin, may be particularly important for social behavior. Collectively, these data point to the serotonin system as a prime candidate for treatment development in a subgroup of children defined by a robust, heritable biomarker.
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Affiliation(s)
- C L Muller
- Vanderbilt Brain Institute, Vanderbilt University, 465 21st Avenue South, Nashville, TN 37232, USA.
| | - A M J Anacker
- Department of Psychiatry, Columbia University, 1051 Riverside Drive, Mail Unit 78, New York, NY 10032, USA.
| | - J Veenstra-VanderWeele
- Sackler Institute for Developmental Psychobiology, Department of Psychiatry, Columbia University; Center for Autism and the Developing Brain, New York Presbyterian Hospital; New York State Psychiatric Institute, 1051 Riverside Drive, Mail Unit 78, New York, NY 10032, USA.
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Faja S, Dawson G, Aylward E, Wijsman EM, Webb SJ. Early event-related potentials to emotional faces differ for adults with autism spectrum disorder and by serotonin transporter genotype. Clin Neurophysiol 2016; 127:2436-47. [PMID: 27178863 DOI: 10.1016/j.clinph.2016.02.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 01/11/2016] [Accepted: 02/11/2016] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To test differences in neural sensitivity to facial expressions, including expressions with open versus closed mouths, exhibited by (1) adults with autism spectrum disorder (ASD) compared to neurotypical adults, and by (2) short versus long serotonin transporter allele (SLC6A4) carriers. METHODS Event related potentials (ERPs) to happy, fearful, and neutral expressions were collected from neurotypical adults (n=25) and adults with ASD (n=27)-of whom 32 had short and 13 had homozygous long SLC6A4 alleles. RESULTS In the neurotypical group, we confirmed that the N170, VPP and EPN, but not the P1, were influenced by emotional expressions, and determined the EPN was the earliest component modulated by open mouth. Compared to the neurotypical group, individuals with ASD exhibited differences in EPN amplitude in response to open versus closed mouths and in hemispheric distribution. Across groups, short serotonin transporter allele carriers had reduced P1 amplitude compared to long allele carriers. CONCLUSIONS Individuals with ASD exhibited a different pattern of neural response when encoding and recognizing facial expressions at the EPN component. Across groups, SLC6A4 allele type modulated early sensory attention at the P1. SIGNIFICANCE These results provide insight into the nature of early responses to emotional information according to genetic variation and clinical condition.
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Affiliation(s)
- Susan Faja
- University of Washington, Department of Psychology, Box 351525, Seattle, WA 98195, USA
| | - Geraldine Dawson
- University of Washington, Department of Psychology, Box 351525, Seattle, WA 98195, USA; University of Washington, Department of Psychiatry and Behavioral Sciences, Box 356560, Room BB1644, Seattle, WA 98195, USA
| | - Elizabeth Aylward
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Ellen M Wijsman
- University of Washington, Department of Medicine, Division of Medical Genetics, Box 356420, Seattle, WA 98195, USA; University of Washington, Department of Biostatistics, Box 357232, Seattle, WA 98195, USA
| | - Sara Jane Webb
- University of Washington, Department of Psychiatry and Behavioral Sciences, Box 356560, Room BB1644, Seattle, WA 98195, USA.
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Golub MS, Bulleri AM, Hogrefe CE, Sherwood RJ. Bone growth in juvenile rhesus monkeys is influenced by 5HTTLPR polymorphisms and interactions between 5HTTLPR polymorphisms and fluoxetine. Bone 2015; 79:162-9. [PMID: 26067181 PMCID: PMC4511468 DOI: 10.1016/j.bone.2015.05.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/12/2015] [Accepted: 05/31/2015] [Indexed: 01/02/2023]
Abstract
Male rhesus monkeys received a therapeutic oral dose of the selective serotonin reuptake inhibitor (SSRI) fluoxetine daily from 1 to 3 years of age. Puberty is typically initiated between 2 and 3 years of age in male rhesus and reproductive maturity is reached at 4 years. The study group was genotyped for polymorphisms in the monoamine oxidase A (MAOA) and serotonin transporter (SERT) genes that affect serotonin neurotransmission. Growth was assessed with morphometrics at 4 month intervals and radiographs of long bones were taken at 12 month intervals to evaluate skeletal growth and maturation. No effects of fluoxetine, or MAOA or SERT genotype were found for growth during the first year of the study. Linear growth began to slow during the second year of the study and serotonin reuptake transporter (SERT) long polymorphic region (5HTTLPR) polymorphism effects with drug interactions emerged. Monkeys with two SERT 5HTTLPR L alleles (LL, putative greater transcription) had 25-39% less long bone growth, depending on the bone, than monkeys with one S and one L allele (SL). More advanced skeletal maturity was also seen in the LL group, suggesting earlier onset of puberty. An interaction between 5HTTLPR polymorphisms and fluoxetine was identified for femur and tibia growth; the 5HTTLPR effect was seen in controls (40% less growth for LL) but not in the fluoxetine treated group (10% less growth for LL). A role for serotonin in peripubertal skeletal growth and maturation has not previously been investigated but may be relevant to treatment of children with SSRIs.
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Affiliation(s)
- Mari S Golub
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616, USA.
| | - Alicia M Bulleri
- California National Primate Research Center, University of California, Davis, Davis, CA 95616, USA
| | - Casey E Hogrefe
- California National Primate Research Center, University of California, Davis, Davis, CA 95616, USA
| | - Richard J Sherwood
- Division of Morphological Sciences and Biostatistics, Boonshoft School of Medicine, Wright State University, Dayton, OH 45434, USA
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Genestine M, Lin L, Durens M, Yan Y, Jiang Y, Prem S, Bailoor K, Kelly B, Sonsalla PK, Matteson PG, Silverman J, Crawley JN, Millonig JH, DiCicco-Bloom E. Engrailed-2 (En2) deletion produces multiple neurodevelopmental defects in monoamine systems, forebrain structures and neurogenesis and behavior. Hum Mol Genet 2015. [PMID: 26220976 DOI: 10.1093/hmg/ddv301] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Many genes involved in brain development have been associated with human neurodevelopmental disorders, but underlying pathophysiological mechanisms remain undefined. Human genetic and mouse behavioral analyses suggest that ENGRAILED-2 (EN2) contributes to neurodevelopmental disorders, especially autism spectrum disorder. In mouse, En2 exhibits dynamic spatiotemporal expression in embryonic mid-hindbrain regions where monoamine neurons emerge. Considering their importance in neuropsychiatric disorders, we characterized monoamine systems in relation to forebrain neurogenesis in En2-knockout (En2-KO) mice. Transmitter levels of serotonin, dopamine and norepinephrine (NE) were dysregulated from Postnatal day 7 (P7) to P21 in En2-KO, though NE exhibited the greatest abnormalities. While NE levels were reduced ∼35% in forebrain, they were increased 40 -: 75% in hindbrain and cerebellum, and these patterns paralleled changes in locus coeruleus (LC) fiber innervation, respectively. Although En2 promoter was active in Embryonic day 14.5 -: 15.5 LC neurons, expression diminished thereafter and gene deletion did not alter brainstem NE neuron numbers. Significantly, in parallel with reduced NE levels, En2-KO forebrain regions exhibited reduced growth, particularly hippocampus, where P21 dentate gyrus granule neurons were decreased 16%, suggesting abnormal neurogenesis. Indeed, hippocampal neurogenic regions showed increased cell death (+77%) and unexpectedly, increased proliferation. Excess proliferation was restricted to early Sox2/Tbr2 progenitors whereas increased apoptosis occurred in differentiating (Dcx) neuroblasts, accompanied by reduced newborn neuron survival. Abnormal neurogenesis may reflect NE deficits because intra-hippocampal injections of β-adrenergic agonists reversed cell death. These studies suggest that disruption of hindbrain patterning genes can alter monoamine system development and thereby produce forebrain defects that are relevant to human neurodevelopmental disorders.
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Affiliation(s)
- Matthieu Genestine
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers
| | - Lulu Lin
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers, Graduate School of Biological Sciences, Rutgers
| | - Madel Durens
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers, Graduate School of Biological Sciences, Rutgers
| | - Yan Yan
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers, Graduate School of Biological Sciences, Rutgers
| | - Yiqin Jiang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers
| | - Smrithi Prem
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers
| | - Kunal Bailoor
- Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Brian Kelly
- Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Patricia K Sonsalla
- Department of Neurology, Rutgers Robert Wood Johnson Medical School, Rutgers
| | - Paul G Matteson
- Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Jill Silverman
- MIND Institute, University of California Davis School of Medicine, Sacramento, CA, USA
| | - Jacqueline N Crawley
- MIND Institute, University of California Davis School of Medicine, Sacramento, CA, USA
| | - James H Millonig
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers, Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Emanuel DiCicco-Bloom
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers, Graduate School of Biological Sciences, Rutgers, Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA and
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Chen Y, Huang WC, Séjourné J, Clipperton-Allen AE, Page DT. Pten Mutations Alter Brain Growth Trajectory and Allocation of Cell Types through Elevated β-Catenin Signaling. J Neurosci 2015; 35:10252-67. [PMID: 26180201 PMCID: PMC6605343 DOI: 10.1523/jneurosci.5272-14.2015] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 06/04/2015] [Accepted: 06/11/2015] [Indexed: 02/04/2023] Open
Abstract
Abnormal patterns of head and brain growth are a replicated finding in a subset of individuals with autism spectrum disorder (ASD). It is not known whether risk factors associated with ASD and abnormal brain growth (both overgrowth and undergrowth) converge on common biological pathways and cellular mechanisms in the developing brain. Heterozygous mutations in PTEN (PTEN(+/-)), which encodes a negative regulator of the PI3K-Akt-mTOR pathway, are a risk factor for ASD and macrocephaly. Here we use the developing cerebral cortex of Pten(+/-) mice to investigate the trajectory of brain overgrowth and underlying cellular mechanisms. We find that overgrowth is detectable from birth to adulthood, is driven by hyperplasia, and coincides with excess neurons at birth and excess glia in adulthood. β-Catenin signaling is elevated in the developing Pten(+/-) cortex, and a heterozygous mutation in Ctnnb1 (encoding β-catenin), itself a candidate gene for ASD and microcephaly, can suppress Pten(+/-) cortical overgrowth. Thus, a balance of Pten and β-catenin signaling regulates normal brain growth trajectory by controlling cell number, and imbalance in this relationship can result in abnormal brain growth. SIGNIFICANCE STATEMENT We report that Pten haploinsufficiency leads to a dynamic trajectory of brain overgrowth during development and altered scaling of neuronal and glial cell populations. β-catenin signaling is elevated in the developing cerebral cortex of Pten haploinsufficient mice, and a heterozygous mutation in β-catenin, itself a candidate gene for ASD and microcephaly, suppresses Pten(+/-) cortical overgrowth. This leads to the new insight that Pten and β-catenin signaling act in a common pathway to regulate normal brain growth trajectory by controlling cell number, and disruption of this pathway can result in abnormal brain growth.
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Affiliation(s)
- Youjun Chen
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458
| | - Wen-Chin Huang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458
| | - Julien Séjourné
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458
| | | | - Damon T Page
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458
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Abstract
BACKGROUND Increasing evidence suggests that autism is associated with abnormal white-matter (WM) anatomy and impaired brain 'connectivity'. While myelin plays a critical role in synchronized brain communication, its aetiological role in autistic symptoms has only been indirectly addressed by WM volumetric, relaxometry and diffusion tensor imaging studies. A potentially more specific measure of myelin content, termed myelin water fraction (MWF), could provide improved sensitivity to myelin alteration in autism. METHOD We performed a cross-sectional imaging study that compared 14 individuals with autism and 14 age- and IQ-matched controls. T 1 relaxation times (T 1), T 2 relaxation times (T 2) and MWF values were compared between autistic subjects, diagnosed using the Autism Diagnostic Interview - Revised (ADI-R), with current symptoms assessed using the Autism Diagnostic Observation Schedule (ADOS) and typical healthy controls. Correlations between T 1, T 2 and MWF values with clinical measures [ADI-R, ADOS, and the Autism Quotient (AQ)] were also assessed. RESULTS Individuals with autism showed widespread WM T 1 and MWF differences compared to typical controls. Within autistic individuals, worse current social interaction skill as measured by the ADOS was related to reduced MWF although not T 1. No significant differences or correlations with symptoms were observed with respect to T 2. CONCLUSIONS Autistic individuals have significantly lower global MWF and higher T 1, suggesting widespread alteration in tissue microstructure and biochemistry. Areas of difference, including thalamic projections, cerebellum and cingulum, have previously been implicated in the disorder; however, this is the first study to specifically indicate myelin alteration in these regions.
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Affiliation(s)
- S C L Deoni
- Advanced Baby Imaging Laboratory,School of Engineering, Brown University,Providence, RI,USA
| | - J R Zinkstok
- Department of Forensic and Neurodevelopmental Sciences,Institute of Psychiatry, King's College London,London,UK
| | - E Daly
- Department of Forensic and Neurodevelopmental Sciences,Institute of Psychiatry, King's College London,London,UK
| | - C Ecker
- Department of Forensic and Neurodevelopmental Sciences,Institute of Psychiatry, King's College London,London,UK
| | - S C R Williams
- Department of Neuroimaging,Institute of Psychiatry, King's College London,London,UK
| | - D G M Murphy
- Department of Forensic and Neurodevelopmental Sciences,Institute of Psychiatry, King's College London,London,UK
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Schauder KB, Muller CL, Veenstra-VanderWeele J, Cascio CJ. Genetic Variation in Serotonin Transporter Modulates Tactile Hyperresponsiveness in ASD. Res Autism Spectr Disord 2015; 10:93-100. [PMID: 25558276 PMCID: PMC4281265 DOI: 10.1016/j.rasd.2014.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Several lines of evidence implicate dysfunction of the serotonin (5-HT) system in autism spectrum disorder (ASD). Specifically, the serotonin transporter (5-HTT, SERT) has been scrutinized as an ASD candidate risk gene. SERT plays key roles in the development of circuits that underlie sensory function, particularly in the somatosensory system. One previous study in ASD found association of a rare, hyperfunctional SERT variant with sensory aversion, but studies of common SERT variants have never examined sensory symptoms in ASD. Using standardized caregiver assessments of sensory function in children, we evaluated patterns of sensory responsiveness in 47 children with ASD and 38 typically developing (TD) children. Study participants were genotyped for the functional SERT promoter polymorphisms, 5-HTTLPR and rs25531, to test the hypothesis that the higher expressing genotypes would be associated with hyperresponsiveness to touch, a common sensory aversion in ASD. All measures of sensory hypo- and hyperresponsiveness were increased in children with ASD, with hyporesponsive sensory patterns negatively correlated to age and hyperresponsive sensory patterns positively correlated to repetitive behavior. Strikingly, high-expressing SERT genotypes were associated with increased tactile hyperresponsiveness in the ASD group. Our findings indicate genetic variation that increases SERT function may specifically impact somatosensory processing in ASD.
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Affiliation(s)
- Kimberly B. Schauder
- Department of Clinical and Social Sciences in Psychology, University of Rochester, P.O. Box 270266, Rochester, NY 14627-0266
| | | | - Jeremy Veenstra-VanderWeele
- Department of Psychiatry, Columbia University, 1080 Ft. Washington Ave, New York, NY 10032
- New York State Psychiatric Institute, 1051 Riverside Dr., New York, NY 10032
- Center for Autism and the Developing Brain, New York Presbyterian Hospital/Cornell University/Columbia University, 21 Bloomingdale Rd, White Plains, NY 10605
| | - Carissa J. Cascio
- Department of Psychiatry, Vanderbilt University School of Medicine, 1601 23 Ave. South, Nashville, TN 37212
- Vanderbilt Kennedy Center, 110 Magnolia Circle, Nashville, TN 37203
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Ciranna L, Catania MV. 5-HT7 receptors as modulators of neuronal excitability, synaptic transmission and plasticity: physiological role and possible implications in autism spectrum disorders. Front Cell Neurosci 2014; 8:250. [PMID: 25221471 PMCID: PMC4145633 DOI: 10.3389/fncel.2014.00250] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/06/2014] [Indexed: 12/22/2022] Open
Abstract
Serotonin type 7 receptors (5-HT7) are expressed in several brain areas, regulate brain development, synaptic transmission and plasticity, and therefore are involved in various brain functions such as learning and memory. A number of studies suggest that 5-HT7 receptors could be potential pharmacotherapeutic target for cognitive disorders. Several abnormalities of serotonergic system have been described in patients with autism spectrum disorder (ASD), including abnormal activity of 5-HT transporter, altered blood and brain 5-HT levels, reduced 5-HT synthesis and altered expression of 5-HT receptors in the brain. A specific role for 5-HT7 receptors in ASD has not yet been demonstrated but some evidence implicates their possible involvement. We have recently shown that 5-HT7 receptor activation rescues hippocampal synaptic plasticity in a mouse model of Fragile X Syndrome, a monogenic cause of autism. Several other studies have shown that 5-HT7 receptors modulate behavioral flexibility, exploratory behavior, mood disorders and epilepsy, which include core and co-morbid symptoms of ASD. These findings further suggest an involvement of 5-HT7 receptors in ASD. Here, we review the physiological roles of 5-HT7 receptors and their implications in Fragile X Syndrome and other ASD.
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Affiliation(s)
- Lucia Ciranna
- Department of Biomedical Sciences, University of Catania Catania, Italy
| | - Maria Vincenza Catania
- Institute of Neurological Sciences, the National Research Council of Italy (CNR) Catania, Italy ; Laboratory of Neurobiology, IRCCS Oasi Maria SS Troina, Italy
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Wassink TH, Hazlett HC, Davis LK, Reiss AL, Piven J. Testing for association of the monoamine oxidase A promoter polymorphism with brain structure volumes in both autism and the fragile X syndrome. J Neurodev Disord 2014; 6:6. [PMID: 24669826 PMCID: PMC3987046 DOI: 10.1186/1866-1955-6-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 03/05/2014] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Autism and the fragile X syndrome (FXS) are related to each other genetically and symptomatically. A cardinal biological feature of both disorders is abnormalities of cerebral cortical brain volumes. We have previously shown that the monoamine oxidase A (MAOA) promoter polymorphism is associated with cerebral cortical volumes in children with autism, and we now sought to determine whether the association was also present in children with FXS. METHODS Participants included 47 2-year-old Caucasian boys with FXS, some of whom also had autism, as well as 34 2-year-old boys with idiopathic autism analyzed in a previous study. The MAOA promoter polymorphism was genotyped and tested for relationships with gray and white matter volumes of the cerebral cortical lobes and cerebro-spinal fluid volume of the lateral ventricles. RESULTS MAOA genotype effects in FXS children were the same as those previously observed in idiopathic autism: the low activity MAOA promoter polymorphism allele was associated with increased gray and white matter volumes in all cerebral lobes. The effect was most pronounced in frontal lobe gray matter and all three white matter regions: frontal gray, F = 4.39, P = 0.04; frontal white, F = 5.71, P = 0.02; temporal white, F = 4.73, P = 0.04; parieto-occipital white, F = 5.00, P = 0.03. Analysis of combined FXS and idiopathic autism samples produced P values for these regions <0.01 and effect sizes of approximately 0.10. CONCLUSIONS The MAOA promoter polymorphism is similarly associated with brain structure volumes in both idiopathic autism and FXS. These data illuminate a number of important aspects of autism and FXS heritability: a genetic effect on a core biological trait of illness, the specificity/generalizability of the genetic effect, and the utility of examining individual genetic effects on the background of a single gene disorder such as FXS.
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Affiliation(s)
- Thomas H Wassink
- Department of Psychiatry, University of Iowa Carver College of Medicine, 1-191 MEB, Iowa City, Iowa 52242, USA.
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Clipperton-Allen AE, Page DT. Pten haploinsufficient mice show broad brain overgrowth but selective impairments in autism-relevant behavioral tests. Hum Mol Genet 2014; 23:3490-505. [PMID: 24497577 DOI: 10.1093/hmg/ddu057] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Accelerated head and brain growth (macrocephaly) during development is a replicated biological finding in a subset of individuals with autism spectrum disorder (ASD). However, the relationship between brain overgrowth and the behavioral and cognitive symptoms of ASD is poorly understood. The PI3K-Akt-mTOR pathway regulates cellular growth; several genes encoding negative regulators of this pathway are ASD risk factors, including PTEN. Mutations in PTEN have been reported in individuals with ASD and macrocephaly. We report that brain overgrowth is widespread in Pten germline haploinsufficient (Pten(+/-)) mice, reflecting Pten mRNA expression in the developing brain. We then ask if broad brain overgrowth translates into general or specific effects on the development of behavior and cognition by testing Pten(+/-) mice using assays relevant to ASD and comorbidities. Deficits in social behavior were observed in both sexes. Males also showed abnormalities related to repetitive behavior and mood/anxiety. Females exhibited circadian activity and emotional learning phenotypes. Widespread brain overgrowth together with selective behavioral impairments in Pten(+/-) mice raises the possibility that most brain areas and constituent cell types adapt to an altered trajectory of growth with minimal impact on the behaviors tested in our battery; however, select areas/cell types relevant to social behavior are more vulnerable or less adaptable, thus resulting in social deficits. Probing dopaminergic neurons as a candidate vulnerable cell type, we found social behavioral impairments in mice with Pten conditionally inactivated in dopaminergic neurons that are consistent with the possibility that desynchronized growth in key cell types may contribute to ASD endophenotypes.
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Affiliation(s)
- Amy E Clipperton-Allen
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter 33458, FL, USA
| | - Damon T Page
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter 33458, FL, USA
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Abstract
UNLABELLED Autism spectrum disorder (ASD) is a common and severe neuro-developmental disorder in early childhood which is defined by social and communication deficits and repetitive and stereotypic behaviours. The aetiology of ASD remains poorly understood. Susceptibility to development of ASD has significant environmental components, in addition to the profound genetic heritability. Few genes have been associated to the risk for ASD development. There is substantial evidence implicating chronic neurological inflammation and immune dysregulation leading to upregulation of inflammatory cytokines in the ASD brain, probably due to altered blood-brain barrier function. The immune system is characterized by excessive and skewed cytokine responses, modulated T cell reactivity, decreased regulation and production of immunosuppressive cytokines, modified NK function and increased autoantibody production. CONCLUSION The perinatal environment generates vulnerability to chronic neuro-inflammation in the brain associated with profound modulation and dysregulation in the immune system leading to the rapid development of ASD in genetically susceptible children.
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Affiliation(s)
- Daniela Briceno Noriega
- Cell Biology and Immunology Group, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands
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Wang CC, Lin HC, Chan YH, Gean PW, Yang YK, Chen PS. 5-HT1A-receptor agonist modified amygdala activity and amygdala-associated social behavior in a valproate-induced rat autism model. Int J Neuropsychopharmacol 2013; 16:2027-39. [PMID: 23823694 DOI: 10.1017/S1461145713000473] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Accumulating evidence suggests that dysfunction of the amygdala is related to abnormal fear processing, anxiety, and social behaviors noted in autistic spectrum disorders (ASDs). In addition, studies have shown that disrupted brain serotonin homeostasis is linked to ASD. With a valproate (VPA)-induced rat ASD model, we investigated the possible role of amygdala serotonin homeostasis in autistic phenotypes and further explored the underlying mechanism. We first discovered that the distribution of tryptophan hydroxylase immunoreactivity in the caudal raphe system was modulated on postnatal day (PD) 28 of the VPA-exposed offspring. Then, we found a significantly higher serotonin transporter availability in the amygdala of the VPA-exposed offspring on PD 56 by using single photon emission computed tomography and computed tomography co-registration following injection of (123)I-labeled 2-((2-(dimethylamino)methyl)phenyl)thio)-5-iodophenylamine((123)I[ADAM]). Furthermore, treatment with 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a 5-HT1A receptor agonist, increased social interaction and improved fear memory extinction in the VPA-exposed offspring. 8-OH-DPAT treatment also reversed the characteristics of miniature excitatory post-synaptic currents as well as paired pulse facilitation observed in lateral amygdala slices. These results provided further evidence to support the role of the amygdala in characteristic behavioral changes in the rat ASD model. The serotonergic projections that modulate the amygdala function might play a certain role in the development and treatment of behavioral symptoms exhibited in individuals with ASD.
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Oblak A, Gibbs TT, Blatt GJ. Reduced serotonin receptor subtypes in a limbic and a neocortical region in autism. Autism Res 2013; 6:571-83. [PMID: 23894004 DOI: 10.1002/aur.1317] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 06/17/2013] [Indexed: 11/09/2022]
Abstract
Autism is a behaviorally defined, neurological disorder with symptom onset before the age of 3. Abnormalities in social-emotional behaviors are a core deficit in autism, and are characterized by impaired reciprocal-social interaction, lack of facial expressions, and the inability to recognize familiar faces. The posterior cingulate cortex (PCC) and fusiform gyrus (FG) are two regions within an extensive limbic-cortical network that contribute to social-emotional behaviors. Evidence indicates that changes in brains of individuals with autism begin prenatally. Serotonin (5-HT) is one of the earliest expressed neurotransmitters, and plays an important role in synaptogenesis, neurite outgrowth, and neuronal migration. Abnormalities in 5-HT systems have been implicated in several psychiatric disorders, including autism, as evidenced by immunology, imaging, genetics, pharmacotherapy, and neuropathology. Although information is known regarding peripheral 5-HT in autism, there is emerging evidence that 5-HT systems in the central nervous system, including various 5-HT receptor subtypes and transporters, are affected in autism. The present study demonstrated significant reductions in 5-HT1A receptor-binding density in superficial and deep layers of the PCC and FG, and in the density of 5-HT(2A) receptors in superficial layers of the PCC and FG. A significant reduction in the density of serotonin transporters (5-HTT) was also found in the deep layers of the FG, but normal levels were demonstrated in both layers of the PCC and superficial layers of the FG. This study provides potential substrates for decreased 5-HT modulation/innervation in the autism brain, and implicate two 5-HT receptor subtypes as potential neuromarkers for novel or existing pharmacotherapies.
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Affiliation(s)
- Adrian Oblak
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts
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Kinast K, Peeters D, Kolk SM, Schubert D, Homberg JR. Genetic and pharmacological manipulations of the serotonergic system in early life: neurodevelopmental underpinnings of autism-related behavior. Front Cell Neurosci 2013; 7:72. [PMID: 23781172 PMCID: PMC3679613 DOI: 10.3389/fncel.2013.00072] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 04/30/2013] [Indexed: 12/28/2022] Open
Abstract
Serotonin, in its function as neurotransmitter, is well-known for its role in depression, autism and other neuropsychiatric disorders, however, less known as a neurodevelopmental factor. The serotonergic system is one of the earliest to develop during embryogenesis and early changes in serotonin levels can have large consequences for the correct development of specific brain areas. The regulation and functioning of serotonin is influenced by genetic risk factors, such as the serotonin transporter polymorphism in humans. This polymorphism is associated with anxiety-related symptoms, changes in social behavior, and cortical gray and white matter changes also seen in patients suffering from autism spectrum disorders (ASD). The human polymorphism can be mimicked by the knockout of the serotonin transporter in rodents, which are as a model system therefore vital to explore the precise neurobiological mechanisms. Moreover, there are pharmacological challenges influencing serotonin in early life, like prenatal/neonatal exposure to selective serotonin reuptake inhibitors (SSRI) in depressed pregnant women. There is accumulating evidence that this dysregulation of serotonin during critical phases of brain development can lead to ASD-related symptoms in children, and reduced social behavior and increased anxiety in rodents. Furthermore, prenatal valproic acid (VPA) exposure, a mood stabilizing drug which is also thought to interfere with serotonin levels, has the potency to induce ASD-like symptoms and to affect the development of the serotonergic system. Here, we review and compare the neurodevelopmental and behavioral consequences of serotonin transporter gene variation, and prenatal SSRI and VPA exposure in the context of ASD.
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Affiliation(s)
- Karsten Kinast
- Behavioural Neurogenetics, Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen Medical Centre Nijmegen, Netherlands
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Wiggins JL, Swartz JR, Martin DM, Lord C, Monk CS. Serotonin transporter genotype impacts amygdala habituation in youth with autism spectrum disorders. Soc Cogn Affect Neurosci 2013; 9:832-8. [PMID: 23526151 DOI: 10.1093/scan/nst039] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Failure of the amygdala to habituate, or decrease response intensity, to repeatedly presented faces may be one mechanism by which individuals with autism spectrum disorders (ASD) develop and maintain social symptoms. However, genetic influences on habituation in ASD have not been examined. We hypothesized that serotonin transporter-linked promoter region (5-HTTLPR) genotype affects change in amygdala response to repeated sad faces differently in individuals with ASD vs healthy controls. Forty-four youth with ASD and 65 controls aged 8-19 years were genotyped and underwent an event-related functional magnetic resonance imaging scan where they identified the gender of emotional faces presented for 250 ms. The first half of the run was compared with the second half to assess habituation. 5-HTTLPR genotype influences amygdala habituation to sad faces differently for individuals with ASD vs controls. The genotype-by-diagnosis-by-run half interaction was driven by individuals with ASD and low expressing genotypes (S/S, S/L(G) and L(G)/L(G)), who trended toward sensitization (increase in amygdala activation) and whose habituation scores significantly differed from individuals with ASD and higher expressing genotypes (L(A)/L(A), S/L(A) and L(A)/L(G)) as well as controls with low expressing genotypes. Our results show that amygdala response to social stimuli in ASD, which may contribute to social symptoms, is genetically influenced.
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Affiliation(s)
- Jillian Lee Wiggins
- Department of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA
| | - Johnna R Swartz
- Department of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA
| | - Donna M Martin
- Department of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USADepartment of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USADepartment of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA
| | - Catherine Lord
- Department of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA
| | - Christopher S Monk
- Department of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USADepartment of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USADepartment of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USADepartment of Psychology, Department of Pediatrics, Neuroscience Program, Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA, Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA, and Department of Psychiatry and Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA
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Gadow KD, DeVincent CJ, Siegal VI, Olvet DM, Kibria S, Kirsch SF, Hatchwell E. Allele-specific associations of 5-HTTLPR/rs25531 with ADHD and autism spectrum disorder. Prog Neuropsychopharmacol Biol Psychiatry 2013; 40:292-7. [PMID: 23123360 PMCID: PMC3522768 DOI: 10.1016/j.pnpbp.2012.10.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/15/2012] [Accepted: 10/23/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND The aims of the present study were to examine the association between a common serotonin transporter gene (SLC6A4) polymorphism 5-HTTLPR/rs25531 with severity of attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) symptoms. METHODS Mothers and teachers completed a validated DSM-IV-referenced rating scale for ADHD and ASD symptoms in 118 children with ASD. RESULTS Analyses indicated that children with at least one copy of the S or L(G) allele obtained significantly more severe maternal ratings of hyperactivity (p=0.001; ηp(2)=0.097) and impulsivity (p=0.027; ηp(2)=0.044) but not inattention (p=0.061; ηp(2)=0.032), controlling for ASD severity, than children homozygous for the L(A) allele. Conversely, mothers' ratings indicated that children with L(A)/L(A) genotype had more severe ASD social deficits than S or L(G) allele carriers (p=0.003; ηp(2)=0.081), controlling for ADHD symptom severity. Teachers' ratings though consistent with mothers' ratings of hyperactivity and social deficits were marginally significant (p=0.07/p=0.09). There was some evidence that the magnitude of parent-teacher agreement regarding symptom severity varied as a function of the child's genotype. CONCLUSION The 5-HTTLPR/rs25531 polymorphism or its correlates may modulate severity of ADHD and ASD symptoms in children with ASD, but in different ways. These tentative, hypothesis-generating findings require replication with larger independent samples.
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Affiliation(s)
- Kenneth D. Gadow
- Department of Psychiatry and Behavioral Sciences, Stony Brook University, Stony Brook, NY 11794-8790, Phone: (631) 632-8858, FAX: (631) 632-8953,
| | - Carla J. DeVincent
- Department of Radiology, Stony Brook Medicine, Stony Brook, NY 11794-8460, Phone: (631) 638-2136,
| | - Victoria I. Siegal
- Department of Pathology, Stony Brook University, Stony Brook, NY 11794-8088,
| | - Doreen M. Olvet
- Molecular Imaging and Neuropathology Division (MIND), New York State Psychiatric Institute, Columbia University, 1051 Riverside Drive, Unit 42, New York, NY 10032, USA, Hillside Hospital
| | - Saniya Kibria
- School of Medicine, Stony Brook University, Stony Brook, NY 11794-8088,
| | - Sarah F. Kirsch
- School of Medicine, Stony Brook University, Stony Brook, NY 11794-8088,
| | - Eli Hatchwell
- Department of Pathology, Stony Brook University, Stony Brook, NY 11794-8088,
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Moy SS, Nonneman RJ, Shafer GO, Nikolova VD, Riddick NV, Agster KL, Baker LK, Knapp DJ. Disruption of social approach by MK-801, amphetamine, and fluoxetine in adolescent C57BL/6J mice. Neurotoxicol Teratol 2013; 36:36-46. [PMID: 22898204 DOI: 10.1016/j.ntt.2012.07.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 07/28/2012] [Accepted: 07/30/2012] [Indexed: 11/23/2022]
Abstract
Autism is a severe neurodevelopmental disorder, diagnosed on the basis of core behavioral symptoms. Although the mechanistic basis for the disorder is not yet known, genetic analyses have suggested a role for abnormal excitatory/inhibitory signaling systems in brain, including dysregulation of glutamatergic neurotransmission. In mice, the constitutive knockdown of NMDA receptors leads to social deficits, repetitive behavior, and self-injurious responses that reflect aspects of the autism clinical profile. However, social phenotypes differ with age: mice with reduced NMDA-receptor function exhibit hypersociability in adolescence, but markedly deficient sociability in adulthood. The present studies determined whether acute disruption of NMDA neurotransmission leads to exaggerated social approach, similar to that observed with constitutive disruption, in adolescent C57BL/6J mice. The effects of MK-801, an NMDA receptor antagonist, were compared with amphetamine, a dopamine agonist, and fluoxetine, a selective serotonin reuptake inhibitor, on performance in a three-chamber choice task. Results showed that acute treatment with MK-801 led to social approach deficits at doses without effects on entry numbers. Amphetamine also decreased social preference, but increased number of entries at every dose. Fluoxetine (10 mg/kg) had selective effects on social novelty preference. Withdrawal from a chronic ethanol regimen decreased activity, but did not attenuate sociability. Low doses of MK-801 and amphetamine were also evaluated in a marble-burying assay for repetitive behavior. MK-801, at a dose that did not disrupt sociability or alter entries, led to a profound reduction in marble-burying. Overall, these findings demonstrate that moderate alteration of NMDA, dopamine, or serotonin function can attenuate social preference in wild type mice.
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Roberts TP, Gandal M, Siegel SJ, Vianney-rodrigues P, Welsh JP. Autism spectrum disorders. Transl Neurosci 2012. [DOI: 10.1017/cbo9780511980053.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Flood ZC, Engel DLJ, Simon CC, Negherbon KR, Murphy LJ, Tamavimok W, Anderson GM, Janušonis S. Brain growth trajectories in mouse strains with central and peripheral serotonin differences: relevance to autism models. Neuroscience 2012; 210:286-95. [PMID: 22450231 DOI: 10.1016/j.neuroscience.2012.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 03/01/2012] [Accepted: 03/03/2012] [Indexed: 10/28/2022]
Abstract
The genetic heterogeneity of autism spectrum disorders (ASDs) suggests that their underlying neurobiology involves dysfunction at the neural network level. Understanding these neural networks will require a major collaborative effort and will depend on validated and widely accepted animal models. Many mouse models have been proposed in autism research, but the assessment of their validity often has been limited to measuring social interactions. However, two other well-replicated findings have been reported in ASDs: transient brain overgrowth in early postnatal life and elevated 5-HT (serotonin) levels in blood platelets (platelet hyperserotonemia). We examined two inbred mouse strains (C57BL/6 and BALB/c) with respect to these phenomena. The BALB/c strain is less social and exhibits some other autistic-like behaviors. In addition, it has a lower 5-HT synthesis rate in the central nervous system due to a single-nucleotide polymorphism in the tryptophan hydroxylase 2 (Tph2) gene. The postnatal growth of brain mass was analyzed with mixed-effects models that included litter effects. The volume of the hippocampal complex and the thickness of the somatosensory cortex were measured in 3D-brain reconstructions from serial sections. The postnatal whole-blood 5-HT levels were assessed with high-performance liquid chromatography. With respect to the BALB/c strain, the C57BL/6 strain showed transient brain overgrowth and persistent blood hyperserotonemia. The hippocampal volume was permanently enlarged in the C57BL/6 strain, with no change in the adult brain mass. These results indicate that, in mice, autistic-like shifts in the brain and periphery may be associated with less autistic-like behaviors. Importantly, they suggest that consistency among behavioral, anatomical, and physiological measures may expedite the validation of new and previously proposed mouse models of autism, and that the construct validity of models should be demonstrated when these measures are inconsistent.
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Affiliation(s)
- Z C Flood
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
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Nordahl CW, Scholz R, Yang X, Buonocore MH, Simon T, Rogers S, Amaral DG. Increased rate of amygdala growth in children aged 2 to 4 years with autism spectrum disorders: a longitudinal study. ACTA ACUST UNITED AC 2012; 69:53-61. [PMID: 22213789 DOI: 10.1001/archgenpsychiatry.2011.145] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Precocious amygdala enlargement is commonly observed in young children with autism. However, the age at which abnormal amygdala enlargement begins and the relative growth trajectories of the amygdala and total brain remain unclear. OBJECTIVE To determine whether the rate of amygdala growth is abnormal and disproportionate to total brain growth in very young children with autism spectrum disorders (ASDs). DESIGN Longitudinal structural magnetic resonance imaging study. SETTING Neuroimaging and diagnostic assessments were performed at an academic medical center. Participants were recruited from the community. PARTICIPANTS Baseline scans were acquired in 132 boys (85 with ASD and 47 control subjects with typical development [TD]; mean age, 37 months). Longitudinal magnetic resonance images were acquired in 70 participants (45 with ASD and 25 TD controls) 1 year later. MAIN OUTCOME MEASURE Amygdala volumes and total cerebral volumes (TCVs) were evaluated at both time points, and 1-year growth rates were calculated. RESULTS The amygdala was larger in children with ASD at both time points, but the magnitude of enlargement was greater at time 2. The TCV was also enlarged in the children with ASD by the same magnitude at both time points. When we controlled for TCV, amygdala enlargement remained significant at both time points. The rate of amygdala growth during this 1-year interval was faster in children with ASD than in TD controls. The rate of TCV growth did not differ between groups. Post hoc exploratory analyses revealed 3 patterns of amygdala and TCV growth rates in the ASD group. CONCLUSIONS Disproportionate amygdala enlargement is present by 37 months of age in ASD. The amygdala continues to grow at an increased rate, but substantial heterogeneity exists in amygdala and TCV growth patterns. Future studies aimed at clinical characterization of different growth patterns could have implications for choice and outcomes of treatment and behavioral therapy.
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Affiliation(s)
- Christine Wu Nordahl
- MIND Institute, University of California, Davis, School of Medicine, Sacramento, CA 95817, USA
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Raznahan A, Lee Y, Vaituzis C, Tran L, Mackie S, Tiemeier H, Clasen L, Lalonde F, Greenstein D, Pierson R, Giedd JN. Allelic variation within the putative autism spectrum disorder risk gene homeobox A1 and cerebellar maturation in typically developing children and adolescents. Autism Res 2012; 5:93-100. [PMID: 22359339 DOI: 10.1002/aur.238] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 11/02/2011] [Indexed: 12/13/2022]
Abstract
Homeobox A1 (HOXA1) has been proposed as a candidate gene for autism spectrum disorder (ASD) as it regulates embryological patterning of hind-brain structures implicated in autism neurobiology. In line with this notion, a nonsynonymous single nucleotide polymorphism within a highly conserved domain of HOXA1--A218G (rs10951154)--has been linked to both ASD risk, and cross-sectional differences in superior posterior lobar cerebellar anatomy in late adulthood. Despite evidence for early onset and developmentally dynamic cerebellar involvement in ASD, little is known of the relationship between A218G genotype and maturation of the cerebellum over early development. We addressed this issue using 296 longitudinally acquired structural magnetic resonance imaging brain scans from 116 healthy individuals between 5 and 23 years of age. Mixed models were used to compare the relationship between age and semi-automated measures of cerebellar volume in A-homozygotes (AA) and carriers of the G allele (Gcar). Total cerebellar volume increased between ages of 5 and 23 years in both groups. However, this was accelerated in the Gcar relative to the AA group (Genotype-by-age interaction term, P = 0.03), and driven by genotype-dependent differences in the rate of bilateral superior posterior lobar volume change with age (P = 0.002). Resultantly, although superior posterior lobar volume did not differ significantly between genotype groups at age 5 (P = 0.9), by age 23 it was 12% greater in Gcar than AA (P = 0.002). Our results suggest that common genetic variation within this putative ASD risk gene has the capacity to modify the development of cerebellar systems implicated in ASD neurobiology.
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Affiliation(s)
- Armin Raznahan
- Child Psychiatry Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
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Ameis SH, Szatmari P. Imaging-genetics in autism spectrum disorder: advances, translational impact, and future directions. Front Psychiatry 2012; 3:46. [PMID: 22615702 PMCID: PMC3351673 DOI: 10.3389/fpsyt.2012.00046] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 04/23/2012] [Indexed: 12/29/2022] Open
Abstract
Autism Spectrum Disorder (ASD) refers to a group of heterogeneous neurodevelopmental disorders that are unified by impairments in reciprocal social communication and a pattern of inflexible behaviors. Recent genetic advances have resolved some of the complexity of the genetic architecture underlying ASD by identifying several genetic variants that contribute to the disorder. Different etiological pathways associated with ASD may converge through effects on common molecular mechanisms, such as synaptogenesis, neuronal motility, and axonal guidance. Recently, with more sophisticated techniques, neuroimaging, and neuropathological studies have provided some consistency of evidence that altered structure, activity, and connectivity within complex neural networks is present in ASD, compared to typically developing children. The imaging-genetics approach promises to help bridge the gap between genetic variation, resultant biological effects on the brain, and production of complex neuropsychiatric symptoms. Here, we review recent findings from the developing field of imaging-genetics applied to ASD. Studies to date have indicated that relevant risk genes are associated with alterations in circuits that mediate socio-emotional, visuo-spatial, and language processing. Longitudinal studies ideally focused on early development, in conjunction with investigation for gene-gene, and gene-environment interactions may move the promise of imaging-genetics in ASD closer to the clinical domain.
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Affiliation(s)
- Stephanie H Ameis
- Department of Psychiatry, The Hospital for Sick Children, University of Toronto Toronto, ON, Canada
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Veenstra-VanderWeele J, Blakely RD. Networking in autism: leveraging genetic, biomarker and model system findings in the search for new treatments. Neuropsychopharmacology 2012; 37:196-212. [PMID: 21937981 PMCID: PMC3238072 DOI: 10.1038/npp.2011.185] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 08/05/2011] [Accepted: 08/06/2011] [Indexed: 12/20/2022]
Abstract
Autism Spectrum Disorder (ASD) is a common neurodevelopmental disorder affecting approximately 1% of children. ASD is defined by core symptoms in two domains: negative symptoms of impairment in social and communication function, and positive symptoms of restricted and repetitive behaviors. Available treatments are inadequate for treating both core symptoms and associated conditions. Twin studies indicate that ASD susceptibility has a large heritable component. Genetic studies have identified promising leads, with converging insights emerging from single-gene disorders that bear ASD features, with particular interest in mammalian target of rapamycin (mTOR)-linked synaptic plasticity mechanisms. Mouse models of these disorders are revealing not only opportunities to model behavioral perturbations across species, but also evidence of postnatal rescue of brain and behavioral phenotypes. An intense search for ASD biomarkers has consistently pointed to elevated platelet serotonin (5-HT) levels and a surge in brain growth in the first 2 years of life. Following a review of the diversity of ASD phenotypes and its genetic origins and biomarkers, we discuss opportunities for translation of these findings into novel ASD treatments, focusing on mTor- and 5-HT-signaling pathways, and their possible intersection. Paralleling the progress made in understanding the root causes of rare genetic syndromes that affect cognitive development, we anticipate progress in models systems using bona fide ASD-associated molecular changes that have the potential to accelerate the development of ASD diagnostics and therapeutics.
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Affiliation(s)
- Jeremy Veenstra-VanderWeele
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
- Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Randy D Blakely
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
- Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA
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Duerden EG, Mak-Fan KM, Taylor MJ, Roberts SW. Regional differences in grey and white matter in children and adults with autism spectrum disorders: an activation likelihood estimate (ALE) meta-analysis. Autism Res 2011; 5:49-66. [PMID: 22139976 DOI: 10.1002/aur.235] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 09/19/2011] [Accepted: 10/20/2011] [Indexed: 01/08/2023]
Abstract
Structural alterations in brain morphology have been inconsistently reported in children compared to adults with autism spectrum disorder (ASD). We assessed these differences by performing meta-analysis on the data from 19 voxel-based morphometry studies. Common findings across the age groups were grey matter reduction in left putamen and medial prefrontal cortex (mPFC) and grey matter increases in the lateral PFC, while white matter decreases were seen mainly in the children in frontostriatal pathways. In the ASD sample, children/adolescents were more likely than adults to have increased grey matter in bilateral fusiform gyrus, right cingulate and insula. Results show that clear maturational differences exist in social cognition and limbic processing regions only in children/adolescents and not in adults with ASD, and may underlie the emotional regulation that improves with age in this population.
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Affiliation(s)
- Emma G Duerden
- Autism Research Unit, The Hospital for Sick Children, Toronto, Ontario, Canada.
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Azmitia EC, Singh JS, Hou XP, Wegiel J. Dystrophic serotonin axons in postmortem brains from young autism patients. Anat Rec (Hoboken) 2011; 294:1653-62. [PMID: 21901837 PMCID: PMC4112519 DOI: 10.1002/ar.21243] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 07/01/2010] [Indexed: 02/04/2023]
Abstract
Autism causes neuropathological changes in varied anatomical loci. A coherent neural mechanism to explain the spectrum of autistic symptomatology has not been proposed because most anatomical researchers focus on point-to-point functional neural systems (e.g., auditory and social networks) rather than considering global chemical neural systems. Serotonergic neurons have a global innervation pattern. Disorders Research Program, AS073234, Program Project (JW). Their cell bodies are found in the midbrain but they project their axons throughout the neural axis beginning in the fetal brain. This global system is implicated in autism by animal models and by biochemical, imaging, pharmacological, and genetics studies. However, no anatomical studies of the 5-HT innervation of autistic donors have been reported. Our review presents immunocytochemical evidence of an increase in 5-HT axons in postmortem brain tissue from autism donors aged 2.8-29 years relative to controls. This increase is observed in the principle ascending fiber bundles of the medial and lateral forebrain bundles, and in the innervation density of the amygdala and the piriform, superior temporal, and parahippocampal cortices. In autistic donors 8 years of age and up, several types of dystrophic 5-HT axons were seen in the termination fields. One class of these dystrophic axons, the thick heavily stained axons, was not seen in the brains of patients with neurodegenerative diseases. These findings provide morphological evidence for the involvement of serotonin neurons in the early etiology of autism, and suggest new therapies may be effective to blunt serotonin's trophic actions during early brain development in children.
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Affiliation(s)
- Efrain C Azmitia
- Department of Biology, New York University, New York, 10003, USA.
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35
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Abstract
The serotonin transporter (SERT) is a key molecule involved in the homeostasis of extracellular levels of serotonin and is regulated developmentally. Genetic deletion of SERT in rodents increases extracellular levels of serotonin and affects cellular processes involved in neocortical circuit assembly such as barrel cortex wiring and cortical interneuron migration. Importantly, pharmacological blockade of SERT during brain development leads to phenotypes relevant to psychiatry in rodents and to an increased risk for autism spectrum disorders in humans. Furthermore, developmental adversity interacts with genetically-driven variations of serotonin function in humans and nonhuman primates to increase the risk for a variety of stress-related phenotypes. In this study, we investigate whether an excess of serotonin affects the migration of neocortical pyramidal neurons during development. Using in utero electroporation combined with time-lapse imaging to specifically monitor pyramidal neurons during late mouse embryogenesis, we show that an excess of serotonin reversibly affects the radial migration of pyramidal neurons. We further identify that the serotonin receptor 5-HT(6) is expressed in pyramidal neuron progenitors and that 5-HT(6) receptor activation replicates the effects of serotonin stimulation. Finally, we show that the positioning of superficial layer pyramidal neurons is altered in vivo in SERT knockout mice. Taken together, these results indicate that a developmental excess of serotonin decreases the migration speed of cortical pyramidal neurons, affecting a fundamental step in the assembly of neural circuits. These findings support the hypothesis that developmental dysregulation of serotonin homeostasis has detrimental effects on neocortical circuit formation and contributes to increased vulnerability to psychiatric disorders.
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Affiliation(s)
- O Riccio
- Department of Mental Health and Psychiatry, University Hospital of Geneva, Geneva, Switzerland,Department of Basic Neurosciences, University of Geneva Medical School, Geneva, Switzerland,Geneva Neuroscience Center, University of Geneva Medical School, Geneva, Switzerland
| | - M Jacobshagen
- Department of Mental Health and Psychiatry, University Hospital of Geneva, Geneva, Switzerland,Department of Basic Neurosciences, University of Geneva Medical School, Geneva, Switzerland,Geneva Neuroscience Center, University of Geneva Medical School, Geneva, Switzerland
| | - B Golding
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva, Switzerland,Geneva Neuroscience Center, University of Geneva Medical School, Geneva, Switzerland
| | - L Vutskits
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva, Switzerland,Geneva Neuroscience Center, University of Geneva Medical School, Geneva, Switzerland,Department of Anesthesiology Pharmacology and Intensive Care, University Hospital of Geneva, Geneva, Switzerland
| | - D Jabaudon
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva, Switzerland,Geneva Neuroscience Center, University of Geneva Medical School, Geneva, Switzerland,Clinic of Neurology, University Hospital of Geneva, Geneva, Switzerland
| | - J P Hornung
- Department of Cellular Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - A G Dayer
- Department of Mental Health and Psychiatry, University Hospital of Geneva, Geneva, Switzerland,Department of Basic Neurosciences, University of Geneva Medical School, Geneva, Switzerland,Geneva Neuroscience Center, University of Geneva Medical School, Geneva, Switzerland,Department of Mental Health and General Psychiatry, University Geneva Medical Center (CMU), Rue Michel-Servet 1, 1211 Genève 4, Switzerland. E-mail:
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36
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Murphy CM, Deeley Q, Daly E, Ecker C, O'Brien F, Hallahan B, Loth E, Toal F, Reed S, Hales S, Robertson D, Craig M, Mullins D, Barker G, Lavender T, Johnston P, Murphy K, Murphy D. Anatomy and aging of the amygdala and hippocampus in autism spectrum disorder: an in vivo magnetic resonance imaging study of Asperger syndrome. Autism Res 2011; 5:3-12. [DOI: 10.1002/aur.227] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 07/20/2011] [Indexed: 11/08/2022]
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Calderoni S, Retico A, Biagi L, Tancredi R, Muratori F, Tosetti M. Female children with autism spectrum disorder: an insight from mass-univariate and pattern classification analyses. Neuroimage 2012; 59:1013-22. [PMID: 21896334 DOI: 10.1016/j.neuroimage.2011.08.070] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/28/2011] [Accepted: 08/21/2011] [Indexed: 11/23/2022] Open
Abstract
Several studies on structural MRI in children with autism spectrum disorders (ASD) have mainly focused on samples prevailingly consisting of males. Sex differences in brain structure are observable since infancy and therefore caution is required in transferring to females the results obtained for males. The neuroanatomical phenotype of female children with ASD (ASDf) represents indeed a neglected area of research. In this study, we investigated for the first time the anatomic brain structures of a sample entirely composed of ASDf (n=38; 2-7 years of age; mean=53 months; SD=18) with respect to 38 female age and non verbal IQ matched controls, using both mass-univariate and pattern classification approaches. The whole brain volumes of each group were compared using voxel-based morphometry (VBM) with diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL) procedure, allowing us to build a study-specific template. Significantly more gray matter (GM) was found in the left superior frontal gyrus (SFG) in ASDf subjects compared to controls. The GM segments obtained in the VBM-DARTEL preprocessing are also classified with a support vector machine (SVM), using the leave-pair-out cross-validation protocol. Then, the recursive feature elimination (SVM-RFE) approach allows for the identification of the most discriminating voxels in the GM segments and these prove extremely consistent with the SFG region identified by the VBM analysis. Furthermore, the SVM-RFE map obtained with the most discriminating set of voxels corresponding to the maximum Area Under the Receiver Operating Characteristic Curve (AUC(max)=0.80) highlighted a more complex circuitry of increased cortical volume in ASDf, involving bilaterally the SFG and the right temporo-parietal junction (TPJ). The SFG and TPJ abnormalities may be relevant to the pathophysiology of ASDf, since these structures participate in some core atypical features of autism.
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Hazlett HC, Poe MD, Gerig G, Styner M, Chappell C, Smith RG, Vachet C, Piven J. Early brain overgrowth in autism associated with an increase in cortical surface area before age 2 years. ACTA ACUST UNITED AC 2011; 68:467-76. [PMID: 21536976 DOI: 10.1001/archgenpsychiatry.2011.39] [Citation(s) in RCA: 297] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Brain enlargement has been observed in 2-year-old children with autism, but the underlying mechanisms are unknown. OBJECTIVE To investigate early growth trajectories in brain volume and cortical thickness. DESIGN Longitudinal magnetic resonance imaging study. SETTING Academic medical centers. PARTICIPANTS Fifty-nine children with autism spectrum disorder (ASD) and 38 control children. INTERVENTION Children were examined at approximately 2 years of age. Magnetic resonance imaging was repeated approximately 24 months later (when aged 4-5 years; 38 children with ASD; 21 controls). MAIN OUTCOME MEASURES Cerebral gray and white matter volumes and cortical thickness. RESULTS We observed generalized cerebral cortical enlargement in individuals with ASD at both 2 and 4 to 5 years of age. Rate of cerebral cortical growth across multiple brain regions and tissue compartments in children with ASD was parallel to that seen in the controls, indicating that there was no increase in rate of cerebral cortical growth during this interval. No cerebellar differences were observed in children with ASD. After controlling for total brain volume, a disproportionate enlargement in temporal lobe white matter was observed in the ASD group. We found no significant differences in cortical thickness but observed an increase in an estimate of surface area in the ASD group compared with controls for all cortical regions measured (temporal, frontal, and parieto-occipital lobes). CONCLUSIONS Our longitudinal magnetic resonance imaging study found generalized cerebral cortical enlargement in children with ASD, with a disproportionate enlargement in temporal lobe white matter. There was no significant difference from controls in the rate of brain growth for this age interval, indicating that brain enlargement in ASD results from an increased rate of brain growth before age 2 years. The presence of increased cortical volume, but not cortical thickness, suggests that early brain enlargement may be associated with increased cortical surface area. Cortical surface area overgrowth in ASD may underlie brain enlargement and implicates a distinct set of pathogenic mechanisms.
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Affiliation(s)
- Heather Cody Hazlett
- Department of Psychiatry, The Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599, USA.
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Tosun D, Dabbs K, Caplan R, Siddarth P, Toga A, Seidenberg M, Hermann B. Deformation-based morphometry of prospective neurodevelopmental changes in new onset paediatric epilepsy. Brain 2011; 134:1003-14. [PMID: 21398377 DOI: 10.1093/brain/awr027] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Epilepsy is a prevalent childhood neurological disorder, but there are few prospective quantitative magnetic resonance imaging studies examining patterns of brain development compared to healthy controls. Controlled prospective investigations initiated at or near epilepsy onset would best characterize the nature, timing and course of neuroimaging abnormalities in paediatric epilepsy. In this study, we report the results of a deformation-based morphometry technique to examine baseline and 2-year prospective neurodevelopmental brain changes in children with new and recent onset localization-related epilepsies (n = 24) and idiopathic generalized epilepsies (n = 20) compared to healthy controls (n = 36). Children with epilepsy demonstrated differences from controls in baseline grey and white matter volumes suggesting antecedent anomalies in brain development, as well as abnormal patterns of prospective brain development that involved not only slowed white matter expansion, but also abnormalities of cortical grey matter development involving both greater and lesser volume changes compared to controls. Furthermore, abnormal neurodevelopmental changes extended outside the cortex affecting several subcortical structures including thalamus, cerebellum, brainstem and pons. Finally, there were significant differences between the epilepsy syndromes (localization-related epilepsies and idiopathic generalized epilepsies) with the idiopathic generalized epilepsies group showing a more disrupted pattern of brain structure both at baseline and over the 2-year interval.
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Affiliation(s)
- Duygu Tosun
- Centre for Imaging of Neurodegenerative Diseases, San Francisco VA Medical Centre, San Francisco, CA, USA.
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40
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Abstract
Brain serotonergic circuitries interact with other neurotransmitter systems on a multitude of different molecular levels. In humans, as in other mammalian species, serotonin (5-HT) plays a modulatory role in almost every physiological function. Furthermore, serotonergic dysfunction is thought to be implicated in several psychiatric and neurodegenerative disorders. We describe the neuroanatomy and neurochemistry of brain serotonergic circuitries. The contribution of emergent in vivo imaging methods to the regional localization of binding site receptors and certain aspects of their functional connectivity in correlation to behavior is also discussed. 5-HT cell bodies, mainly localized in the raphe nuclei, send axons to almost every brain region. It is argued that the specificity of the local chemocommunication between 5-HT and other neuronal elements mainly depends on mechanisms regulating the extracellular concentration of 5-HT the diversity of high-affinity membrane receptors, and their specific transduction modalities.
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Affiliation(s)
- Yves Charnay
- Hôpitaux Universitaires de Genève, Département de Psychiatrie, Service de Neuropsychiatrie, Ch. Du Petit-Bel-Air, 2, CH-1225 Chêne-Bourg, Switzerland.
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41
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Zwaigenbaum L, Scherer S, Szatmari P, Fombonne E, Bryson SE, Hyde K, Anagnostou E, Brian J, Evans A, Hall G, Nicholas D, Roberts W, Smith I, Vaillancourt T, Volden J, Volden J. The NeuroDevNet Autism Spectrum Disorders Demonstration Project. Semin Pediatr Neurol 2011; 18:40-8. [PMID: 21575840 DOI: 10.1016/j.spen.2011.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The NeuroDevNet Autism Spectrum Disorder Demonstration Project interfaces at many levels with the network's research themes and priorities. Our interdisciplinary team aims to improve understanding of genetic factors underlying vulnerability to autism spectrum disorders (ASDs) to develop better diagnostic strategies and, ultimately, to pinpoint molecular pathways relevant to developing biologically based treatments. Linking our existing longitudinal ASD cohorts with both genetics and neuroimaging studies will provide, for the first time, integrated data on how the genetic variation influences brain and behavioral development in ASD. Importantly, as our science progresses and we translate this information to the health care system, we will also educate policy makers, media, and business, so an informed society is prepared to capitalize on new genomic advances and effectively integrate these into health services for the broader community. We believe that this research has the potential to transform assessment and care for individuals with ASD.
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42
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Kistner-Griffin E, Brune CW, Davis LK, Sutcliffe JS, Cox NJ, Cook EH. Parent-of-origin effects of the serotonin transporter gene associated with autism. Am J Med Genet B Neuropsychiatr Genet 2011; 156:139-44. [PMID: 21302342 PMCID: PMC3438509 DOI: 10.1002/ajmg.b.31146] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 10/25/2010] [Indexed: 11/09/2022]
Abstract
A promoter-linked insertion/deletion polymorphism of the serotonin transporter gene (SLC6A4) has been implicated in autism spectrum disorders (ASDs) in numerous family based association studies. However, the results of these investigations have been inconsistent in that both the long and short alleles have been shown to be over-transmitted to affected offspring. In order to further elucidate the relationship between the 5-HTTLPR variant and autism risk, we undertook a thorough study of parent-of-origin effects, maternal genotype effects, and offspring genotype effects in a sample of affected offspring from the Autism Genetic Resource Exchange (AGRE). Both the overall autism phenotype and measures of autism behaviors from the Autism Diagnostic Interview-Revised [Lord et al. (1994); J Autism Dev Disord 24(5): 659–685] were considered. We found evidence of over-transmission (risk allele short, P = 0.012), maternal effects (risk allele long, P = 0.035), and parent-of-origin effects (risk allele short from mother, P = 0.018) of the 5-HTTLPR variant in the AGRE sample. Population- and gender-specific effects were also explored as associations may be heterogeneous across populations and sexes. Parent-of-origin effects of the variant were associated with maternally inherited copies of the short allele that resulted in more impaired overall level of language (P = 0.04). Our study was conducted to further investigate the 5-HTTLPR risk variants by identifying allelic associations that may be population-specific, phenotype-specific, or conferred by maternal or parent-of-origin effects. In light of conflicting observations from previous studies, these are just a few of the possible explanations that deserve attention.
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Affiliation(s)
- Emily Kistner-Griffin
- Division of Biostatistics and Epidemiology, Department of Medicine, Medical University of South Carolina, 86 Jonathon Lucas St., Charleston, SC 29425, USA.
| | - Camille W. Brune
- Institute for Juvenile Research, Department of Psychiatry, University of Illinois-Chicago
| | - Lea K. Davis
- Institute for Juvenile Research, Department of Psychiatry, University of Illinois-Chicago
| | - James S. Sutcliffe
- Departments of Molecular Physiology & Biophysics and Psychiatry, Vanderbilt University, Nashville, TN
| | - Nancy J. Cox
- Section of Genetic Medicine, Departments of Medicine and Human Genetics, University of Chicago
| | - Edwin H. Cook
- Institute for Juvenile Research, Department of Psychiatry, University of Illinois-Chicago
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Lin Z, Canales JJ, Björgvinsson T, Thomsen MM, Qu H, Liu QR, Torres GE, Caine SB. Monoamine transporters: vulnerable and vital doorkeepers. Prog Mol Biol Transl Sci 2011; 98:1-46. [PMID: 21199769 PMCID: PMC3321928 DOI: 10.1016/b978-0-12-385506-0.00001-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transporters of dopamine, serotonin, and norepinephrine have been empirically used as medication targets for several mental illnesses in the last decades. These protein-targeted medications are effective only for subpopulations of patients with transporter-related brain disorders. Since the cDNA clonings in early 1990s, molecular studies of these transporters have revealed a wealth of information about the transporters' structure-activity relationship (SAR), neuropharmacology, cell biology, biochemistry, pharmacogenetics, and the diseases related to the human genes encoding these transporters among related regulators. Such new information creates a unique opportunity to develop transporter-specific medications based on SAR, mRNA, DNA, and perhaps transporter trafficking regulation for a number of highly relevant diseases including substance abuse, depression, schizophrenia, and Parkinson's disease.
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Affiliation(s)
- Zhicheng Lin
- Department of Psychiatry, Harvard Medical School and Division of Alcohol and Drug Abuse, McLean Hospital, Belmont, MA 02478, USA
| | - Juan J. Canales
- Department of Psychology, Behavioural Neuroscience, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
| | - Thröstur Björgvinsson
- Behavioral Health Partial Hospital and Psychology Internship Programs, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
| | - Morgane M. Thomsen
- Department of Psychiatry, Harvard Medical School and Division of Alcohol and Drug Abuse, McLean Hospital, Belmont, MA 02478, USA
| | - Hong Qu
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University. Beijing, 100871 China
| | - Qing-Rong Liu
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Gonzalo E. Torres
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - S. Barak Caine
- Department of Psychiatry, Harvard Medical School and Division of Alcohol and Drug Abuse, McLean Hospital, Belmont, MA 02478, USA
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Hermann BP, Dabbs K, Becker T, Jones JE, Myers y Gutierrez A, Wendt G, Koehn MA, Sheth R, Seidenberg M. Brain development in children with new onset epilepsy: a prospective controlled cohort investigation. Epilepsia 2010; 51:2038-46. [PMID: 20384719 DOI: 10.1111/j.1528-1167.2010.02563.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE To characterize prospective neurodevelopmental changes in brain structure in children with new and recent-onset epilepsy compared to healthy controls. METHODS Thirty-four healthy controls (mean age 12.9 years) and 38 children with new/recent-onset idiopathic epilepsy (mean age 12.9 years) underwent 1.5 T magnetic resonance imaging (MRI) at baseline and 2 years later. Prospective changes in total cerebral and lobar gray and white matter volumes were compared within and between groups. RESULTS Prospective changes in gray matter volume were comparable for the epilepsy and control groups, with significant (p < 0.0001) reduction in total cerebral gray matter, due primarily to significant (p < 0.001) reductions in frontal and parietal gray matter. Prospective white matter volume changes differed between groups. Controls exhibited a significant (p = 0.0012) increase in total cerebral white matter volume due to significant (p < 0.001) volume increases in the frontal, parietal, and temporal lobes. In contrast, the epilepsy group exhibited nonsignificant white matter volume change in the total cerebrum (p = 0.51) as well as across all lobes (all p's > 0.06). The group by white matter volume change interactions were significant for total cerebrum (p = 0.04) and frontal lobe (p = 0.04). DISCUSSION Children with new and recent-onset epilepsy exhibit an altered pattern of brain development characterized by delayed age-appropriate increase in white matter volume. These findings may affect cognitive development through reduced brain connectivity and may also be related to the impairments in executive function commonly reported in this population.
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Affiliation(s)
- Bruce P Hermann
- Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA.
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45
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Wallace GL, Dankner N, Kenworthy L, Giedd JN, Martin A. Age-related temporal and parietal cortical thinning in autism spectrum disorders. Brain 2010; 133:3745-54. [PMID: 20926367 PMCID: PMC2995883 DOI: 10.1093/brain/awq279] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 07/28/2010] [Accepted: 08/05/2010] [Indexed: 11/14/2022] Open
Abstract
Studies of head size and brain volume in autism spectrum disorders have suggested that early cortical overgrowth may be followed by prematurely arrested growth. However, the few investigations quantifying cortical thickness have yielded inconsistent results, probably due to variable ages and/or small sample sizes. We assessed differences in cortical thickness between high-functioning adolescent and young adult males with autism spectrum disorders (n = 41) and matched typically developing males (n = 40). We hypothesized thinner cortex, particularly in frontal, parietal and temporal regions, for individuals with autism spectrum disorders in comparison with typically developing controls. Furthermore, we expected to find an age × diagnosis interaction: with increasing age, more pronounced cortical thinning would be observed in autism spectrum disorders than typically developing participants. T(1)-weighted magnetization prepared rapid gradient echo 3 T magnetic resonance imaging scans were acquired from high-functioning males with autism spectrum disorders and from typically developing males matched group-wise on age (range 12-24 years), intelligence quotient (≥ 85) and handedness. Both gyral-level and vertex-based analyses revealed significantly thinner cortex in the autism spectrum disorders group that was located predominantly in left temporal and parietal regions (i.e. the superior temporal sulcus, inferior temporal, postcentral/superior parietal and supramarginal gyri). These findings remained largely unchanged after controlling for intelligence quotient and after accounting for psychotropic medication usage and comorbid psychopathology. Furthermore, a significant age × diagnosis interaction was found in the left fusiform/inferior temporal cortex: participants with autism spectrum disorders had thinner cortex in this region with increasing age to a greater degree than did typically developing participants. Follow-up within group comparisons revealed significant age-related thinning in the autism spectrum disorders group but not in the typically developing group. Both thinner temporal and parietal cortices during adolescence and young adulthood and discrepantly accelerated age-related cortical thinning in autism spectrum disorders suggest that a second period of abnormal cortical growth (i.e. greater thinning) may be characteristic of these disorders.
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Affiliation(s)
- Gregory L Wallace
- Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, MD 20892-1366, USA.
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Nijmeijer JS, Hartman CA, Rommelse NN, Altink ME, Buschgens CJ, Fliers EA, Franke B, Minderaa RB, Ormel J, Sergeant JA, Verhulst FC, Buitelaar JK, Hoekstra PJ. Perinatal risk factors interacting with catechol O-methyltransferase and the serotonin transporter gene predict ASD symptoms in children with ADHD. J Child Psychol Psychiatry 2010; 51:1242-50. [PMID: 20868372 PMCID: PMC2970704 DOI: 10.1111/j.1469-7610.2010.02277.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Symptoms of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) often co-occur. Given the previously found familiality of ASD symptoms in children with ADHD, addressing these symptoms may be useful for genetic association studies, especially for candidate gene findings that have not been consistently replicated for ADHD. METHODS We studied the association of the catechol O-methyltransferase (COMT) Val158Met polymorphism and the serotonin transporter (SLC6A4/SERT/5-HTT) 5-HTTLPR insertion/deletion polymorphism with ASD symptoms in children with ADHD, and whether these polymorphisms would interact with pre- and perinatal risk factors, i.e., maternal smoking during pregnancy and low birth weight. Analyses were performed using linear regression in 207 Dutch participants with combined type ADHD of the International Multicenter ADHD Genetics (IMAGE) study, and repeated in an independent ADHD sample (n =439) selected from the TRracking Adolescents' Individual Lives Survey (TRAILS). Dependent variables were the total and subscale scores of the Children's Social Behavior Questionnaire (CSBQ). RESULTS No significant main effects of COMT Val158Met, 5-HTTLPR, maternal smoking during pregnancy and low birth weight on ASD symptoms were found. However, the COMT Val/Val genotype interacted with maternal smoking during pregnancy in increasing stereotyped behavior in the IMAGE sample (p =.008); this interaction reached significance in the TRAILS sample after correction for confounders (p =.02). In the IMAGE sample, the 5-HTTLPR S/S genotype interacted with maternal smoking during pregnancy, increasing problems in social interaction (p =.02), and also interacted with low birth weight, increasing rigid behavior (p =.03). Findings for 5-HTTLPR in the TRAILS sample were similar, albeit for related CSBQ subscales. CONCLUSIONS These findings suggest gene-environment interaction effects on ASD symptoms in children with ADHD.
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Affiliation(s)
- Judith S. Nijmeijer
- Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Catharina A. Hartman
- Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Nanda N.J. Rommelse
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Department of Clinical Neuropsychology, VU University Amsterdam, Amsterdam, The Netherlands
| | - Marieke E. Altink
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Karakter, Child and Adolescent Psychiatry University Center Nijmegen, Nijmegen, The Netherlands
| | - Cathelijne J.M. Buschgens
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Ellen A. Fliers
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Youth Department, Lucertis, Parnassia-Bavo-Group, Rotterdam, The Netherlands
| | - Barbara Franke
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Department of Human Genetics, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Ruud B. Minderaa
- Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Johan Ormel
- Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Joseph A. Sergeant
- Department of Clinical Neuropsychology, VU University Amsterdam, Amsterdam, The Netherlands
| | - Frank C. Verhulst
- Department of Child and Adolescent Psychiatry, Erasmus-MC Sophia, Rotterdam, The Netherlands
| | - Jan K. Buitelaar
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands,Karakter, Child and Adolescent Psychiatry University Center Nijmegen, Nijmegen, The Netherlands
| | - Pieter J. Hoekstra
- Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Wiggins JL, Peltier SJ, Ashinoff S, Weng SJ, Carrasco M, Welsh RC, Lord C, Monk CS. Using a self-organizing map algorithm to detect age-related changes in functional connectivity during rest in autism spectrum disorders. Brain Res 2010; 1380:187-97. [PMID: 21047495 DOI: 10.1016/j.brainres.2010.10.102] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 10/25/2010] [Accepted: 10/26/2010] [Indexed: 11/18/2022]
Abstract
Healthy individuals show robust functional connectivity during rest, which is stronger in adults than in children. Connectivity occurs between the posterior and anterior portions of the default network, a group of structures active in the absence of a task, including the posterior cingulate cortex and the superior frontal gyrus. Previous studies found weaker posterior-anterior connectivity in the default network in adults and adolescents with autism spectrum disorders (ASD). However, these studies used small a priori regions of interest ("seeds") to calculate connectivity. Since seed location for all participants was chosen based on controls' brains, these studies' analyses are more tailored to controls than individuals with ASD. An alternative is to use a data-driven approach, such as self-organizing maps (SOM), to create a reference for each participant to calculate connectivity. We used individualized resting-state clusters identified by an SOM algorithm to corroborate previous findings of weaker posterior-anterior connectivity in the ASD group and examine age-related changes in the ASD and control groups. Thirty-nine adolescents with ASD and 41 controls underwent a 10-minute, eyes-open, resting-state functional MRI scan. The SOM analysis revealed that adolescents with ASD versus controls have weaker connectivity between the posterior hub of the default network and the right superior frontal gyrus. Additionally, controls have larger increases in connectivity with age compared to the ASD group. These findings indicate that SOM is a complementary method for calculating connectivity in a clinical population. Additionally, adolescents with ASD have a different developmental trajectory of the default network compared to controls.
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Murphy DG, Beecham J, Craig M, Ecker C. Autism in adults. New biologicial findings and their translational implications to the cost of clinical services. Brain Res 2011; 1380:22-33. [PMID: 20969835 DOI: 10.1016/j.brainres.2010.10.042] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 09/22/2010] [Accepted: 10/13/2010] [Indexed: 11/21/2022]
Abstract
There is increasing evidence that children with autism spectrum disorder (ASD) have differences in brain growth trajectory. However, the neurobiological basis of ASD in adults is poorly understood. We report evidence that brain anatomy and aging in people with ASD is significantly different as compared to controls-so that in adulthood they no longer have a significantly larger overall brain volume, but they do have anatomical and functional abnormalities in frontal lobe, basal ganglia and the limbic system. Further we present preliminary evidence that females have significantly greater abnormalities in brain than males to express the same symptom severity of ASD (i.e. the female brain is "protective" against developing ASD). Also we present preliminary evidence that, in adults, clinical services for autism in the United Kingdom are experiencing very significantly increased demand; but that just over 50% of people seeking a diagnosis from one expert service do not have ASD. This consumes very significant health care resources, and so we need to identify new cost-effective methods to aid current diagnostic practice. We present initial evidence offering proof of concept that brain anatomy can be used to accurately distinguish adults with autism from healthy controls, and from some other neurodevelopmental disorders (ADHD). Hence further studies are required to determine if sMRI can become an aid to current diagnostic practice in young adults with ASD. Lastly we report evidence that differences in serotonin, glutamate and GABA may partially explain neuroanatomical and neurofunctional abnormalities in people with ASD, and that genetic influences on brain maturation vary across the lifespan (with 5-HT transporter polymorphisms having significant modulatory effects in children but not adults).
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Endo T, Kitamura H, Tamura R, Egawa J, Sugai T, Fukui N, Suzuki Y, Someya T. 5-HTTLPR polymorphism influences prefrontal neurochemical metabolites in autism spectrum disorder. Psychiatry Res 2010; 183:170-3. [PMID: 20619617 DOI: 10.1016/j.pscychresns.2010.04.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 03/19/2010] [Accepted: 04/28/2010] [Indexed: 12/20/2022]
Abstract
We investigated whether the promoter region of the serotonin transporter gene (5-HTTLPR) polymorphism influenced neurochemical metabolism in 26 individuals with autism spectrum disorder. Individuals with the S/S genotype of the 5-HTTLPR polymorphism showed significantly lower levels of N-acetylaspartate/creatine in the right medial prefrontal cortex compared with those with the S/L genotype.
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Affiliation(s)
- Taro Endo
- Department of Psychiatry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
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Grafodatskaya D, Chung B, Szatmari P, Weksberg R. Autism spectrum disorders and epigenetics. J Am Acad Child Adolesc Psychiatry 2010; 49:794-809. [PMID: 20643313 DOI: 10.1016/j.jaac.2010.05.005] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 05/05/2010] [Accepted: 05/10/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE Current research suggests that the causes of autism spectrum disorders (ASD) are multifactorial and include both genetic and environmental factors. Several lines of evidence suggest that epigenetics also plays an important role in ASD etiology and that it might, in fact, integrate genetic and environmental influences to dysregulate neurodevelopmental processes. The objective of this review is to illustrate how epigenetic modifications that are known to alter gene expression without changing primary DNA sequence may play a role in the etiology of ASD. METHOD In this review, we summarize current knowledge about epigenetic modifications to genes and genomic regions possibly involved in the etiology of ASD. RESULTS Several genetic syndromes comorbid with ASD, which include Rett, Fragile X, Prader-Willi, Angelman, and CHARGE (Coloboma of the eye, Heart defects, Atresia of the nasal choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness), all demonstrate dysregulation of epigenetic marks or epigenetic mechanisms. We report also on genes or genomic regions exhibiting abnormal epigenetic regulation in association with either syndromic (15q11-13 maternal duplication) or nonsyndromic forms of ASD. Finally, we discuss the state of current knowledge regarding the etiologic role of environmental factors linked to both the development of ASD and epigenetic dysregulation. CONCLUSION Data reviewed in this article highlight a variety of situations in which epigenetic dysregulation is associated with the development of ASD, thereby supporting a role for epigenetics in the multifactorial etiologies of ASD.
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