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Jiang W, King TZ, Turner JA. Imaging Genetics Towards a Refined Diagnosis of Schizophrenia. Front Psychiatry 2019; 10:494. [PMID: 31354550 PMCID: PMC6639711 DOI: 10.3389/fpsyt.2019.00494] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 06/24/2019] [Indexed: 01/31/2023] Open
Abstract
Current diagnoses of schizophrenia and related psychiatric disorders are classified by phenomenological principles and clinical descriptions while ruling out other symptoms and conditions. Specific biomarkers are needed to assist the current diagnostic system. However, complicated gene and environment interactions induce great disease heterogeneity. This unclear etiology and heterogeneity raise difficulties in distinguishing schizophrenia-related effects. Simultaneously, the overlap in symptoms, genetic variations, and brain alterations in schizophrenia and related psychiatric disorders raises similar difficulties in determining disease-specific effects. Imaging genetics is a unique methodology to assess the impact of genetic factors on both brain structure and function. More importantly, imaging genetics builds a bridge to understand the behavioral and clinical implications of genetics and neuroimaging. By characterizing and quantifying the brain measures affected in psychiatric disorders, imaging genetics is contributing to identifying potential biomarkers for schizophrenia and related disorders. To date, candidate gene analysis, genome-wide association studies, polygenetic risk score analysis, and large-scale collaborative studies have made contributions to the understanding of schizophrenia with the potential to serve as biomarkers. Despite limitations, imaging genetics remains promising as more aggregative, clustering methods and imaging genetics-compatible clinical assessments are employed in future studies. We review imaging genetics' contribution to our understanding of the heterogeneity within schizophrenia and the commonalities across schizophrenia and other diagnostic borders, and we will discuss whether imaging genetics is ready to form its own diagnostic system.
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Affiliation(s)
- Wenhao Jiang
- Department of Psychology and the Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Tricia Z King
- Department of Psychology and the Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Jessica A Turner
- Department of Psychology and the Neuroscience Institute, Georgia State University, Atlanta, GA, United States.,Mind Research Network, Albuquerque, NM, United States
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Hou G, Yang X, Yuan TF. Hippocampal asymmetry: differences in structures and functions. Neurochem Res 2013; 38:453-60. [PMID: 23283696 DOI: 10.1007/s11064-012-0954-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/11/2012] [Accepted: 12/19/2012] [Indexed: 12/12/2022]
Abstract
The structural asymmetry of bilateral hippocampus in mammals has been well recognized. Recent findings highlighted the accompanying functional asymmetries, as well as the molecular differences of the hippocampus. The present paper summarized these recent advances in understanding the hippocampal asymmetries at molecular, circuit and functional levels. Additionally, the addition of new neurons to the hippocampal circuit during adulthood is asymmetrical. We conclude that these differences in molecules and structures of bilateral hippocampus determined the variances in functionality between the two sides.
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Affiliation(s)
- Gonglin Hou
- Centre of Cognitive Research, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
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Abstract
Schizophrenia (SZP) has been historically referred to as "dementia praecox" because of the recognition that its onset is associated with deficits in memory, attention and visuospatial orientation. We wondered whether there is evidence for additional cognitive decline late in the course of chronic SZP. This review examined the evidence (1) for cognitive decline late in the course of chronic SZP, (2) for how often the late cognitive decline occurs, and (3) whether the cognitive decline in late-life SZP is related to pathophysiology of SZP versus the superimposition of another type of dementia. A PUBMED search was performed combining the MESH terms schizophrenia and dementia, cognitive decline, cognitive impairment and cognitive deficits. A manual search of article bibliographies was also performed. We included longitudinal clinical studies employing standard tests of cognition. Cross-sectional studies and those that did not test cognition through standard cognitive tests were excluded. The initial search produced 3898 studies. Employing selection criteria yielded twenty-three studies. Our data extraction tool included the number of patients in the study, whether a control group was present, the age of patients at baseline and follow-up, the study setting (inpatients versus outpatients), the cognitive tests employed, study duration, and results. Only three longitudinal studies tested for dementia using Diagnostic and statistical manual of mental disorder (DSM) or International classification of disease (ICD) criteria and compared them to controls: two studies demonstrated an increase in the prevalence of dementia and one did not. Twenty longitudinal studies tested for one or more cognitive domains without employing standard criteria for dementia: twelve studies demonstrated a heterogeneous pattern of cognitive decline and eight did not. Studies generally did not control for known risk factors for cognitive impairment such as education, vascular risk factors, apolipoprotein (ApoE) genotype and family history. The evidence for late cognitive decline in SZP is mixed, but, slightly more studies suggest that it occurs. If it occurs, it is unclear whether it is related to SZP or other risks for cognitive impairment. Hence, prospective, longitudinal, controlled studies are needed to confirm that there is progressive cognitive decline in chronic SZP which occurs independent of other risk factors for cognitive impairment.
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Abstract
PURPOSE OF REVIEW Schizophrenia is a complex genetic disorder, caused by multiple genetic and environmental factors. Recently, studies have focused on testing specific genetic markers in a known candidate gene for association with endophenotypes. These are measurable characteristics of a disorder that are assumed to be closer to the action of the gene, resulting in higher genetic signal-to-noise ratios. Structural brain parameters have been shown to be useful endophenotypes for studies in psychiatric illnesses. RECENT FINDINGS After reviewing the available studies on the influence of genotype on brain volume in schizophrenia, it is evident that the BDNF and COMT genes are clearly favourites for genetic imaging studies. Results from these studies seem to be quite consistent, with the same associated alleles and direction of brain volume changes. The most frequently investigated polymorphisms suggest that sample sizes of approximately 50-100 patients are sufficient to report consistent findings. Considering the ongoing discussion about the sample size necessary to detect significant associations, however, larger sample sizes are needed. SUMMARY There is sufficient evidence to defend the use of structural neuroimaging as an endophenotype to investigate a complex phenotype such as schizophrenia despite the notion that, so far, no single causal pathway emerges from these studies. Replication studies and larger numbers of patients are essential in this respect.
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Kampman O, Anttila S, Illi A, Mattila KM, Rontu R, Leinonen E, Lehtimäki T. Apolipoprotein E polymorphism is associated with age of onset in schizophrenia. J Hum Genet 2004; 49:355-359. [PMID: 15221639 DOI: 10.1007/s10038-004-0157-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Accepted: 03/26/2004] [Indexed: 12/24/2022]
Abstract
The aims of the study were to investigate the relationship between Apolipoprotein E (APOE) polymorphism, risk of schizophrenia, treatment response to conventional anti-psychotics, and age of onset in schizophrenia. The sample comprised 94 Finnish patients with a DSM-IV diagnosis of schizophrenia. Forty-three of the patients were good responders to conventional anti-psychotics and 51 were classified as non-responders. The control group consisted of 98 healthy blood donors. The APOE allele frequencies (epsilon 2, epsilon 3, and epsilon 4) were 4.8, 72.3, and 22.9% in patients and 7.1, 75.0, and 17.9 in controls. None of the differences between groups were statistically significant. No association between treatment response and APOE genotype was found. Patients with APOE epsilon 4/epsilon 4 genotype had a markedly lower age of onset compared with rest of the sample (p=0.0015), which remained significant when controlling for gender (p=0.02). There was an increasing linear trend between the number of epsilon 3 alleles (0, 1, or 2) and age of onset in schizophrenia (p=0.08). An inverse trend was found between the number of epsilon 4 alleles and age of onset (p=0.07). No relationship between APOE polymorphism and risk for schizophrenia was found. APOE epsilon 4/epsilon 4 genotype may be associated with early onset schizophrenia. APOE epsilon 3 allele may function protectively in later onset in this disease.
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Affiliation(s)
- Olli Kampman
- Medical School, University of Tampere, 33014, Tampere, Finland.
- Department of Psychiatry, Seinäjoki Hospital District, 62200, Seinäjoki, Finland.
| | - Sami Anttila
- Medical School, University of Tampere, 33014, Tampere, Finland
- Laboratory of Atherosclerosis Genetics, Department of Clinical Chemistry, Centre for Laboratory Medicine, Tampere University Hospital, Teiskontie 35, PL 2000, 33521, Tampere, Finland
| | - Ari Illi
- Medical School, University of Tampere, 33014, Tampere, Finland
- Department of Psychiatry, Kanta-Häme Central Hospital, 13530, Hameenlinna, Finland
| | - Kari M Mattila
- Medical School, University of Tampere, 33014, Tampere, Finland
- Laboratory of Atherosclerosis Genetics, Department of Clinical Chemistry, Centre for Laboratory Medicine, Tampere University Hospital, Teiskontie 35, PL 2000, 33521, Tampere, Finland
| | - Riikka Rontu
- Medical School, University of Tampere, 33014, Tampere, Finland
- Laboratory of Atherosclerosis Genetics, Department of Clinical Chemistry, Centre for Laboratory Medicine, Tampere University Hospital, Teiskontie 35, PL 2000, 33521, Tampere, Finland
| | - Esa Leinonen
- Medical School, University of Tampere, 33014, Tampere, Finland
- Department of Psychiatry, Tampere University Hospital, 33380, Pitkaniemi, Finland
| | - Terho Lehtimäki
- Medical School, University of Tampere, 33014, Tampere, Finland
- Laboratory of Atherosclerosis Genetics, Department of Clinical Chemistry, Centre for Laboratory Medicine, Tampere University Hospital, Teiskontie 35, PL 2000, 33521, Tampere, Finland
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Harrison PJ. The hippocampus in schizophrenia: a review of the neuropathological evidence and its pathophysiological implications. Psychopharmacology (Berl) 2004; 174:151-62. [PMID: 15205886 DOI: 10.1007/s00213-003-1761-y] [Citation(s) in RCA: 518] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2003] [Accepted: 11/25/2003] [Indexed: 01/17/2023]
Abstract
This paper puts the case for the hippocampus as being central to the neuropathology and pathophysiology of schizophrenia. The evidence comes from a range of approaches, both in vivo (neuropsychology, structural and functional imaging) and post mortem (histology, morphometry, gene expression, and neurochemistry). Neuropathologically, the main positive findings concern neuronal morphology, organisation, and presynaptic and dendritic parameters. The results are together suggestive of an altered synaptic circuitry or "wiring" within the hippocampus and its extrinsic connections, especially with the prefrontal cortex. These changes plausibly represent the anatomical component of the aberrant functional connectivity that underlies schizophrenia. Glutamatergic pathways are prominently but not exclusively affected. Changes appear somewhat greater in the left hippocampus than the right, and CA1 is relatively uninvolved compared to other subfields. Hippocampal pathology in schizophrenia may be due to genetic factors, aberrant neurodevelopment, and/or abnormal neural plasticity; it is not due to any recognised neurodegenerative process. Hippocampal involvement is likely to be associated with the neuropsychological impairments of schizophrenia rather than with its psychotic symptoms.
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Affiliation(s)
- Paul J Harrison
- Department of Psychiatry, Neurosciences Building, Warneford Hospital, University of Oxford, Oxford, OX3 7JX, UK.
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