An update on the comorbidity of ADHD and ASD: a focus on clinical management

Sodium hydrogen exchanger 9 NHE9 (SLC9A9) and its emerging roles in neuropsychiatric comorbidity

Variations in SLC9A9 gene expression and protein function are associated with multiple human diseases, which range from Attention-deficit/hyperactivity disorder (ADHD) to glioblastoma multiforme. In an effort to determine the full spectrum of human disease associations with SLC9A9, we performed a systematic review of the literature. We also review SLC9A9's biochemistry, protein structure, and function, as well as its interacting partners with the goal of identifying mechanisms of disease and druggable targets. We report gaps in the literature regarding the genes function along with consistent trends in disease associations that can be used to further research into treating the respective diseases. We report that SLC9A9 has strong associations with neuropsychiatric diseases and various cancers. Interestingly, we find strong overlap in SLC9A9 disease associations and propose a novel role for SLC9A9 in neuropsychiatric comorbidity. In conclusion, SLC9A9 is a multifunctional protein that, through both its endosome regulatory function and its protein-protein interaction network, has the ability to modulate signaling axes, such as the PI3K pathway, among others.

Neuropsychopathology of Autism Spectrum Disorder: Complex Interplay of Genetic, Epigenetic, and Environmental Factors

Autism spectrum disorder (ASD) is a complex heterogeneous consortium of pervasive development disorders (PDD) which ranges from atypical autism, autism, and Asperger syndrome affecting brain in the developmental stage. This debilitating neurodevelopmental disorder results in both core as well as associated symptoms. Core symptoms observed in autistic patients are lack of social interaction, pervasive, stereotyped, and restricted behavior while the associated symptoms include irritability, anxiety, aggression, and several comorbid disorders.ASD is a polygenic disorder and is multifactorial in origin. Copy number variations (CNVs) of several genes that regulate the synaptogenesis and signaling pathways are one of the major factors responsible for the pathogenesis of autism. The complex integration of various CNVs cause mutations in the genes which code for molecules involved in cell adhesion, voltage-gated ion-channels, scaffolding proteins as well as signaling pathways (PTEN and mTOR pathways). These mutated genes are responsible for affecting synaptic transmission by causing plasticity dysfunction responsible, in turn, for the expression of ASD.Epigenetic modifications affecting DNA transcription and various pre-natal and post-natal exposure to a variety of environmental factors are also precipitating factors for the occurrence of ASD. All of these together cause dysregulation of glutamatergic signaling as well as imbalance in excitatory: inhibitory pathways resulting in glial cell activation and release of inflammatory mediators responsible for the aberrant social behavior which is observed in autistic patients.In this chapter we review and provide insight into the intricate integration of various genetic, epigenetic, and environmental factors which play a major role in the pathogenesis of this disorder and the mechanistic approach behind this integration.

Patterns of Psychiatric Comorbidity and Genetic Correlations Provide New Insights Into Differences Between Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) share common genetic factors but seem to have specific patterns of psychiatric comorbidities. There are few systematic studies on adults; therefore, we compared psychiatric comorbidities in adults with these two neurodevelopmental disorders using population-based data and analyzed their genetic correlations to evaluate underlying factors.

METHODS

Using data from Norwegian registries, we assessed patterns of psychiatric disorders in adults with ADHD (n = 38,636; 2.3%), ASD (n = 7528; 0.4%), and both diagnoses (n = 1467; 0.1%) compared with the remaining adult population (n = 1,653,575). We calculated their prevalence ratios (PRs) and differences using Poisson regression, also examining sex-specific relations. Genetic correlations (r_g) among ADHD, ASD, and the examined psychiatric disorders were calculated by linkage disequilibrium score regression, exploiting summary statistics from relevant genome-wide association studies.

RESULTS

For all psychiatric comorbidities, PRs differed between ADHD and ASD. Associations were strongest in individuals with ADHD and ADHD+ASD for most comorbidities, in both men and women. The relative prevalence increase of substance use disorder was three times larger in ADHD than in ASD (PR_ADHD, 6.2; 95% confidence interval [CI], 6.1-6.4; PR_ASD, 1.9; 95% CI, 1.7-2.2; p < .001); however, the opposite was true for schizophrenia (PR_ASD, 13.9; 95% CI, 12.7-15.2; PR_ADHD, 4.4; 95% CI, 4.1-4.7; p < .001). Genetic correlations supported these patterns but were significantly different between ADHD and ASD only for the substance use disorder proxies and personality traits (p < .006 for all).

CONCLUSIONS

Adults with ADHD, ASD, or both ADHD and ASD have specific patterns of psychiatric comorbidities. This may partly be explained by differences in underlying genetic factors.

From Toddlerhood to Adolescence: Which Characteristics Among Toddlers with Autism Spectrum Disorder Predict Adolescent Attention Deficit/Hyperactivity Symptom Severity? A Long-Term Follow-Up Study

High rates of attention deficit/hyperactivity disorder (ADHD) comorbidity have been described in autism spectrum disorder (ASD). This study searched for predictors at toddlerhood of the severity of ADHD symptoms at adolescence. The study included 65 participants, (mean age = 13:8 year), diagnosed with ASD at toddlerhood. Participants underwent a comprehensive assessment of cognitive ability, adaptive skills and autism severity at toddlerhood and adolescence. More severe restricted and repetitive behaviors (RRB) in toddlerhood predicted the severity of Inattention symptoms. In addition, more severe RRB and lower adaptive skills in the toddler years significantly predicted the severity of Hyperactivity/Impulsivity symptoms. Adolescents with elevated ADHD symptoms diagnosed at toddlerhood with ASD showed lower cognitive and adaptive skills and more severe autism symptoms.

Altered kynurenine pathway metabolites in a mouse model of human attention-deficit hyperactivity/autism spectrum disorders: A potential new biological diagnostic marker

Deleterious mutations in patchd1 domain containing 1 (PTCHD1) gene have been identified in patients with intellectual disability and/or autism spectrum disorder (ASD). To clarify the causal relationship between Ptchd1 deficiency and behavioral defects relevant to neurodevelopmental disorders, we generated global Ptchd1 knockout (KO) mice. Ptchd1 KO mice displayed hyperlocomotion, increased impulsivity, and lower recognition memory, which resemble attention-deficit hyperactivity disorder (ADHD)-like behaviors. Acute or chronic treatment with atomoxetine ameliorated almost all behavioral deficits in Pthcd1 KO mice. We next determined possible involvement of the kynurenine pathway (KP) metabolites in neurodevelopmental disorders in Ptchd1 KO mice and assessed the potential of KP metabolites as biomarkers for ADHD and/or ASD. Ptchd1 KO mice showed drastic changes in KP metabolite concentrations in the serum and the brain, indicating that the activated KP is associated with ADHD-like behaviors. Our findings indicate that Ptchd1 KO mice can be used as an animal model of human ADHD and/or ASD, and KP metabolites are potential diagnostic biomarkers for neurodevelopmental disorders.

A Case Study of Parent–Child Interaction Therapy for the Treatment of High-Functioning Autism Spectrum Disorder

Youth with autism spectrum disorder (ASD) may have difficulties with compliance, impulsivity, and attention, which can affect daily adaptive functioning leading to disruptions in family social interactions, communication skills, academic achievement, and engagement in the community. Although previous research has identified behavioral treatments such as applied behavior analysis (ABA) therapy for youth with ASD, it is important to explore more interventions that can be effective in decreasing problematic behaviors while also building positive social skill development. This case study illustrates the effectiveness of Parent–Child Interaction Therapy (PCIT) to address behavioral problems in a 7-year-old boy with high-functioning ASD (HF-ASD) and comorbid ADHD. Overall, the results demonstrated a decrease in child challenging behaviors and an increase in child compliance. In addition, the child’s mother increased her use of positive parenting skills and effective commands. This study provides additional support for PCIT for children with ASD, but was not without challenges. These challenges, characteristic of families affected by ASD, and treatment implications for clinicians working with this population are discussed.

Medium-Range Narratives as a Complementary Tool to Principle-Based Prioritization in Sweden: Test Case "ADHD"

In this paper, for the benefit of reflection processes in clinical and in local, regional, and national priority-setting, we aim to develop an ethical theoretical framework that includes both ethical principles and medium-range narratives. We present our suggestion in the particular case of having to choose between treatment interventions for attention deficit hyperactivity disorder (ADHD) and treatment interventions for other conditions or diseases, under circumstances of scarcity. In order to arrive at our model, we compare two distinct ethical approaches: a generalist (principles) approach and a particularist (narratives) approach. Our focus is on Sweden, because in Sweden prioritization in healthcare is uniquely governmentally regulated by the "ethics platform." We will present a (fictional) scenario to analyse the strengths and weaknesses of the generalist principled perspective of the ethics platform and the particularist perspective of narrative ethics. We will suggest an alternative (moderately particularist) approach to prioritization, which we dub a "principles plus medium-range narratives" approach. Notwithstanding the undeniably central role of principles in distributive justice, we claim that medium-range narratives concerning individuals or groups who stand to benefit or lose from ADHD prioritization practices should also be read or listened to and taken into account at all levels of priority-setting. These narratives are expected to ethically optimize clinical priority-setting, as well as that undertaken at local, regional, and national levels.

Social functioning in youth with attention-deficit/hyperactivity disorder and autism spectrum disorder: transdiagnostic commonalities and differences

Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are both neurodevelopmental disorders originating in childhood with high associated impairments and public health significance. There has been growing recognition of the frequent co-occurrence, and potential interrelatedness, between ADHD and ASD without intellectual disability. In fact, the most recent (5th) edition of the DSM is the first to allow ADHD and ASD to be diagnosed in the same individual. The study of transdiagnostic features in ADHD and ASD is important for understanding, and treating, these commonly co-occurring disorders. Social impairment is central to the description and prognosis of both disorders, and many youth with some combination of ADHD and ASD present to clinics for social skills training interventions. However, the aspects of social functioning that are impaired may have both shared and distinct features between the two disorders, relating to some overlapping and some diverse etiologies of social problems in ADHD compared to ASD. These findings have implications for interventions to address social problems in youth with these conditions. We conclude with a discussion about areas for future research and novel intervention targets in youth with ADHD, ASD, and their comorbidity.

Home-cage hypoactivity in mouse genetic models of autism spectrum disorder

Genome-wide association and whole exome sequencing studies from Autism Spectrum Disorder (ASD) patient populations have implicated numerous risk factor genes whose mutation or deletion results in significantly increased incidence of ASD. Behavioral studies of monogenic mutant mouse models of ASD-associated genes have been useful for identifying aberrant neural circuitry. However, behavioral results often differ from lab to lab, and studies incorporating both males and females are often not performed despite the significant sex-bias of ASD. In this study, we sought to investigate the simple, passive behavior of home-cage activity monitoring across multiple 24-h days in four different monogenic mouse models of ASD: Shank3b^-/-, Cntnap2^-/-, Pcdh10^+/-, and Fmr1 knockout mice. Relative to sex-matched wildtype (WT) littermates, we discovered significant home-cage hypoactivity, particularly in the dark (active) phase of the light/dark cycle, in male mice of all four ASD-associated transgenic models. For Cntnap2^-/- and Pcdh10^+/- mice, these activity alterations were sex-specific, as female mice did not exhibit home-cage activity differences relative to sex-matched WT controls. These home-cage hypoactivity alterations differ from activity findings previously reported using short-term activity measurements in a novel open field. Despite circadian problems reported in human ASD patients, none of the mouse models studied had alterations in free-running circadian period. Together, these findings highlight a shared phenotype across several monogenic mouse models of ASD, outline the importance of methodology on behavioral interpretation, and in some genetic lines parallel the male-enhanced phenotypic presentation observed in human ASDs.

Autism spectrum disorders in high secure psychiatric care: a review of literature, future research and clinical directions

Purpose

The purpose of this paper is to review available literature targeting the assessment and management of individuals with an autism spectrum disorder (ASD) admitted to high secure psychiatric care (HSPC). Key areas of examination include the prevalence of ASD in HSPC, how individuals with an ASD differ from other patient groups in clinical and cognitive characteristics, the views of staff regarding patients with an ASD, an exploration of the experiences and quality of life of patients with an ASD, as well as treatment and interventions.

Design/methodology/approach

A review of the published literature.

Findings

Although individuals with an ASD comprise a relatively small proportion of the total HSPC cohort, they appear to be over represented relative to the general population prevalence. Several research projects suggest that individuals with an ASD present with difficulties and needs different to other patient groups, as well as being viewed by staff as potentially vulnerable and requiring a different care approach. Individuals with an ASD report both positive and negative aspects to life in HSPC.

Practical implications

Suggestions are made with regard to how individuals with an ASD might be better managed in HSPC. Following the spirit of various pieces of government legislation such as the Autism Act (2009) and the Equalities Act (2010) the role of a specialist ASD HSPC service is proposed.

Originality/value

This paper provides a detailed review of the research to date exploring the assessment and management of individuals with an ASD detained in HSPC. It outlines key research findings, highlights limitations with it and provides a personal perspective on future research and clinical targets.

ADHD in children and youth: Part 3-Assessment and treatment with comorbid ASD, ID, or prematurity

Attention-deficit hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder. Three position statements have been developed by the Canadian Paediatric Society, following systematic literature reviews. Statement objectives are to: 1) Summarize the current clinical evidence regarding ADHD,2) Establish a standard for ADHD care, and3) Assist Canadian clinicians in making well-informed, evidence-based decisions to enhance care of children and youth with this condition. Specific topics reviewed in Part 3, which focuses on associated autism spectrum disorder, intellectual disability, and prematurity, include the challenges of diagnostic assessment, common presentations, the role of genetics, and treatment, including the benefits of physical activity. Recommendations are based on current guidelines, evidence from the literature, and expert consensus.

Subtyping the Autism Spectrum Disorder: Comparison of Children with High Functioning Autism and Asperger Syndrome

Since Hans Asperger's first description (Arch Psych Nervenkrankh 117:76-136, 1944), through Lorna Wing's translation and definition (Psychol Med 11:115-129, 1981), to its introduction in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM, 1994), Asperger Syndrome has always aroused huge interest and debate, until vanishing in the DSM fifth edition (2013). The debate regarded its diagnostic validity and its differentiation from high functioning autism (HFA). The present study aimed to examine whether AS differed from HFA in clinical profiles and to analyze the impact of DSM-5's innovation. Differences in cognitive, language, school functioning and comorbidities, were revealed when 80 AS and 70 HFA patients (3-18 years) were compared. Results suggested that an AS empirical distinction within autism spectrum disorder should be clinically useful.

Neurodevelopmental Disorders and Adaptive Functions: A Study of Children With Autism Spectrum Disorders (ASD) and/or Attention Deficit and Hyperactivity Disorder (ADHD)

Introduction: Autism spectrum disorder (ASD) and attention deficit and hyperactivity disorder (ADHD) are the two most common neurodevelopmental disorders observed in childhood. The DSM-5 accepts a combined diagnosis of ADHD and ASD, while the DSM-IV did not. The aim of this study was to identify and evaluate the adaptive profile of children and adolescents with a diagnosis of comorbid ADHD and ASD, in comparison with adaptive functioning in subjects with a diagnosis of only ASD or ADHD. Materials and Methods: Ninety-one children (77 boys, 14 girls), aging from 3.1 to 13.4 years (mean age: 8.3 ± 7.2), who met the criteria for a diagnosis of ASD and/or ADHD were enrolled. A neuropsychological evaluation involving cognitive and adaptive assessment was conducted using the Autism Diagnostic Observation Schedule - Second Edition (ADOS-2), the Conners' Parent Rating Scale - Revised: Long Version (CPRS-R), the Wechsler Intelligence Scale - Fourth Edition or the Griffiths Mental Developmental Scales - Extended Revised, the Vineland Adaptive Behaviour Scale - Second Edition (VABS-II). Conclusion: As to the adaptive skills in the three groups evaluated, a worse general profile was ascertained in the ASD and in ASD plus ADHD groups in comparison with respect to the ADHD-only group. With VABS-II evaluation, we found significant differences among the three groups across all domains and combined scores: Communication (F = 18.960; p < 0.001), Socialization (F = 25.410; p < 0.001), Daily Living Skills (F = 19.760; p < 0.001), Motor (F = 9.615; p < 0.001), and Adaptive behavior composite [ABC] (F = 29.370; p < 0.001). Implications of neurodevelopmental double diagnosis such as ASD plus ADHD are discussed.

Sex-Gender Comparisons in Comorbidities of Children and Adolescents With High-Functioning Autism Spectrum Disorder

Over the last few years, new studies focused their attention on the gender-related features in high-functioning autism spectrum disorder (HFA), often leading to controversial results. Another interesting aspect of these subtype of patients is linked to the complexity of clinical presentation, where besides core symptoms, other co-occurrence disorders may complicate the diagnostic evaluation. Therefore, we retrospectively studied 159 HFA patients, male and female, investigating their comorbidities and to find any gender difference. For each patient, were evaluated the presence/absence, type and gender distribution of psychopathological comorbidities, according to DSM-5 diagnostic criteria. The total sample was divided in 100 male and 59 female patients, age and intelligence quotient matched. In our sample, the psychiatric comorbidities observed were Attention Deficit Hyperactivity Disorder, Anxiety Disorders, Depressive Disorders, Bipolar Disorder, Obsessive-Compulsive Disorder, and Anorexia Nervosa. No statistical significant differences were found between male and female HFA patients comorbidities except for Anorexia Nervosa. In both male and female patients, attention deficit and hyperactivity disorder and anxiety disorders were found in high percentage. In conclusion, our investigation showed that a statistical significant difference of comorbidity between male and female HFA patients was found only for AN diagnosis. However, the question about the distinction between female and male HFA patients remains quite interesting and an open area of research for future studies.

Children with autism and attention deficit hyperactivity disorder. Relationships between symptoms and executive function, theory of mind, and behavioral problems

BACKGROUND

The underlying mechanisms of comorbidity between autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) are still unknown. Executive function (EF) deficits and theory of mind (ToM) have been the most investigated cognitive processes.

AIMS

This study proposed to analyze EF, ToM and behavioral problems in children with ASD + ADHD, ADHD, ASD and typical development (TD). The relationship between ADHD and ASD symptoms with EF, ToM and behavioral problems in children with ASD + ADHD was also explored.

METHODS AND PROCEDURES

Participants were 124 children between 7 and 11 years old (22 ASD + ADHD, 35 ADHD, 30 ASD, and 37 TD), matched on age and IQ. Teachers evaluated EF, and parents assessed ToM skills and behavioral problems through Strengths and Difficulties Questionnaire (SDQ).

OUTCOMES AND RESULTS

Children with ASD + ADHD and ADHD showed impairments in EF whereas the difficulties in ToM skills of ASD + ADHD group were similar to ASD group. Inattention symptoms were significantly associated with EF metacognitive deficits and ToM difficulties in ASD + ADHD, while ASD symptoms were associated with total score in behavioral problems.

CONCLUSIONS AND IMPLICATIONS

These findings show the complex difficulties of children with both ASD and ADHD and support the need to take these difficulties into account when designing the treatments.

Measurement considerations in pediatric research on autism spectrum disorders

Studying Autism Spectrum Disorders (ASD) in genetic syndromes has gained interest in the scientific community as a way to elucidate mechanisms and symptom profiles to understand ASD more broadly. Appropriate and adequate measurement of constructs, symptomatology, and outcomes in clinical research is of vital importance in establishing the prevalence of such symptoms and measuring change in symptoms in the context of clinical trials. As such, we provide an overview of the prevalence of ASD, present current diagnostic guidelines, discuss important comorbidities to consider, describe current assessment strategies in assessing ASD, and discuss these within the context of a specific genetic condition to highlight how ASD can be best evaluated.

Role of epigenetic mechanisms in transmitting the effects of neonatal sevoflurane exposure to the next generation of male, but not female, rats

BACKGROUND

Clinical studies report learning disabilities and attention-deficit/hyperactivity disorders in those exposed to general anaesthesia early in life. Rats, primarily males, exposed to GABAergic anaesthetics as neonates exhibit behavioural abnormalities, exacerbated responses to stress, and reduced expression of hypothalamic K+-2Cl- Cl- exporter (Kcc2). The latter is implicated in development of psychiatric disorders, including male predominant autism spectrum disorders. We tested whether parental early life exposure to sevoflurane, the most frequently used anaesthetic in paediatrics, affects the next generation of unexposed rats.

METHODS

Offspring (F1) of unexposed or exposed to sevoflurane on postnatal day 5 Sprague-Dawley rats (F0) were subjected to behavioural and brain gene expression evaluations.

RESULTS

Male, but not female, progeny of sevoflurane-exposed parents exhibited abnormalities in behavioural testing and Kcc2 expression. Male F1 rats of both exposed parents exhibited impaired spatial memory and expression of hippocampal and hypothalamic Kcc2. Offspring of only exposed sires had abnormalities in elevated plus maze and prepulse inhibition of startle, but normal spatial memory and impaired expression of hypothalamic, but not hippocampal, Kcc2. In contrast to exposed F0, their progeny exhibited normal corticosterone responses to stress. Bisulphite sequencing revealed increased CpG site methylation in the Kcc2 promoter in F0 sperm and F1 male hippocampus and hypothalamus that was in concordance with the changes in Kcc2 expression in specific F1 groups.

CONCLUSIONS

Neonatal exposure to sevoflurane can affect the next generation of males through epigenetic modification of Kcc2 expression, while F1 females are at diminished risk.

Anxiety and Mood Disorder in Children With Autism Spectrum Disorder and ADHD

OBJECTIVES

Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur. Understanding the endophenotype of children with both ASD and ADHD may impact clinical management. In this study, we compare the comorbidity of anxiety and mood disorders in children with ASD, with and without ADHD.

METHODS

We performed a cross-sectional study of children with ASD who were enrolled in the Interactive Autism Network, an Internet-mediated, parent-report, autism research registry. Children ages 6 to 17 years with a parent-reported, professional, and questionnaire-verified diagnosis of ASD were included. Data were extracted regarding parent-reported diagnosis and/or treatment of ADHD, anxiety disorder, and mood disorder. ASD severity was measured by using Social Responsiveness Scale total raw scores.

RESULTS

There were 3319 children who met inclusion criteria. Of these, 1503 (45.3%) had ADHD. Comorbid ADHD increased with age (P < .001) and was associated with increased ASD severity (P < .001). A generalized linear model revealed that children with ASD and ADHD had an increased risk of anxiety disorder (adjusted relative risk 2.20; 95% confidence interval 1.97-2.46) and mood disorder (adjusted relative risk 2.72; 95% confidence interval 2.28-3.24) compared with children with ASD alone. Increasing age was the most significant contributor to the presence of anxiety disorder and mood disorder.

CONCLUSIONS

Co-occurrence of ADHD is common in children with ASD. Children with both ASD and ADHD have an increased risk of anxiety and mood disorders. Physicians who care for children with ASD should be aware of the coexistence of these treatable conditions.

Co-occurring psychiatric conditions in autism spectrum disorder

Individuals with autism spectrum disorder (ASD) are at increased risk for experiencing one or more co-occurring psychiatric conditions. When present, these conditions are associated with additional impairment and distress. It is therefore crucial that clinicians and researchers adequately understand and address these challenges. However, due to symptom overlap, diagnostic overshadowing, and ambiguous symptom presentation in ASD, the assessment of co-occurring conditions in ASD is complex and challenging. Likewise, individual difference factors, such as age, intellectual functioning, and gender, may influence the presentation of co-occurring symptoms. Relatedly, a transdiagnostic framework may offer utility in assessing and treating co-occurring conditions. However, with the exception of anxiety disorders, treatment research for co-occurring psychiatric conditions in ASD is relatively limited. Therefore, the present paper aims to summarize and review available research on the most common co-occurring psychiatric disorders in ASD, with a focus on estimated population-based prevalence rates, diagnostic challenges, the influence of individual differences, and assessment guidelines. The utility of a transdiagnostic framework for conceptualizing co-occurring disorders in ASD is discussed, and the state of treatment research for co-occurring disorders is summarized. This study concludes with a summary of the extant literature, as well as recommendations for future research.

Characterizing the Interplay Between Autism Spectrum Disorder and Comorbid Medical Conditions: An Integrative Review

Co-occurring medical disorders and associated physiological abnormalities in individuals with autism spectrum disorder (ASD) may provide insight into causal pathways or underlying biological mechanisms. Here, we review medical conditions that have been repeatedly highlighted as sharing the strongest associations with ASD-epilepsy, sleep, as well as gastrointestinal and immune functioning. We describe within each condition their prevalence, associations with behavior, and evidence for successful treatment. We additionally discuss research aiming to uncover potential aetiological mechanisms. We then consider the potential interaction between each group of conditions and ASD and, based on the available evidence, propose a model that integrates these medical comorbidities in relation to potential shared aetiological mechanisms. Future research should aim to systematically examine the interactions between these physiological systems, rather than considering these in isolation, using robust and sensitive biomarkers across an individual's development. A consideration of the overlap between medical conditions and ASD may aid in defining biological subtypes within ASD and in the development of specific targeted interventions.

Maternal Polycystic Ovary Syndrome and Risk for Attention-Deficit/Hyperactivity Disorder in the Offspring

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is the most common childhood neurodevelopmental disorder, and boys are two to three times more likely to develop ADHD. Maternal polycystic ovary syndrome (PCOS), a common metabolic disorder associated with excess circulating androgens, has been associated with increased risk for autism spectrum disorder in the offspring. In this study, we aimed to investigate whether maternal PCOS increases the risk for ADHD in the offspring.

METHODS

We conducted a matched case-control study using health and population data registers for all children born in Sweden from 1984 to 2008. Maternal PCOS was defined by ICD-coded register diagnosis. The outcome of ADHD was defined as an ICD-coded register diagnosis of ADHD and/or registered prescription of medications to treat ADHD. A total of 58,912 ADHD cases (68.8% male) were identified and matched to 499,998 unaffected controls by sex and birth month and year.

RESULTS

Maternal PCOS increased the odds of offspring ADHD by 42% after adjustment for confounders (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.26-1.58). Exclusion of ADHD cases with comorbid autism spectrum disorder attenuated but did not explain the relationship (OR, 1.34; 95% CI, 1.18-1.52). The risk was somewhat elevated for ADHD with comorbid autism spectrum disorder (OR, 1.76; 95% CI, 1.37-2.26). The risk for ADHD was higher among obese mothers with PCOS (OR, 1.68; 95% CI, 1.31-2.17) and was highest among obese mothers with PCOS and other features of metabolic syndrome (OR, 2.59; 95% CI, 1.02-6.58).

CONCLUSIONS

This study provides evidence that maternal PCOS may subtly influence the neurodevelopment of the offspring, resulting in increased risk for neurodevelopmental disorders such as ADHD.

DSM-5 Changes in Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder: Implications for Comorbid Sleep Issues

Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are the most common neurodevelopmental disorders. Despite significant comorbidity, the previous diagnostic criteria prohibited the simultaneous diagnosis of both disorders. Sleep problems are highly prevalent in both disorders; however, these have been studied independently for ADHD and ASD. In the context of revised criteria in the Diagnostic Statistical Manual of Mental Disorders 5th edition (DSM-5) that allows combined diagnosis of ADHD and ASD, this short review presents an overview of relationship between sleep problems, ADHD and ASD, as well as conceptualizing the shared pathophysiology. The practical considerations for clinical management of sleep problems in combination with ADHD and ASD are also discussed.

Neuropsychological Characteristics of Children with Mixed Autism and ADHD

Clinical heterogeneity is a well-established characteristic of autism spectrum disorder (ASD). While the comorbidity of ASD and ADHD is well known in clinical practice, relatively little research has examined the neuropsychological profile of children with ASD + ADHD. Our study showed significant differences in the neuropsychological characteristics of children with ASD + ADHD compared to those with ASD only. Children with ASD + ADHD showed higher symptoms of anxiety, worse working memory, and less empathy, as measured by the "Reading the Mind in the Eyes." This suggests that having ADHD brings further challenges to individuals with ASD and may negatively impact their management and outcome. Our findings may have implications for clinical assessment as well as for intervention.

Emerging Roles for the Gut Microbiome in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a serious neurodevelopmental disorder that affects one in 45 children in the United States, with a similarly striking prevalence in countries around the world. However, mechanisms underlying its etiology and manifestations remain poorly understood. Although ASD is diagnosed based on the presence and severity of impaired social communication and repetitive behavior, immune dysregulation and gastrointestinal issues are common comorbidities. The microbiome is an integral part of human physiology; recent studies show that changes in the gut microbiota can modulate gastrointestinal physiology, immune function, and even behavior. Links between particular bacteria from the indigenous gut microbiota and phenotypes relevant to ASD raise the important question of whether microbial dysbiosis plays a role in the development or presentation of ASD symptoms. Here we review reports of microbial dysbiosis in ASD. We further discuss potential effects of the microbiota on ASD-associated symptoms, drawing on signaling mechanisms for reciprocal interactions among the microbiota, immunity, gut function, and behavior. In addition, we discuss recent findings supporting a role for the microbiome as an interface between environmental and genetic risk factors that are associated with ASD. These studies highlight the integration of pathways across multiple body systems that together can impact brain and behavior and suggest that changes in the microbiome may contribute to symptoms of neurodevelopmental disease.

Predicting ADHD by Assessment of Rutter's Indicators of Adversity in Infancy

Background

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder with early onset. ADHD is associated with significant morbidity and mortality, partly due to delayed diagnosis. Identification of children at high risk for developing ADHD could lead to earlier diagnosis and potentially change the negative trajectory of the illness for the better. Since early psychosocial adversity is considered to be a likely etiological risk factor for ADHD, markers of this construct may be useful for early identification of children at high risk. Therefore, we sought to investigate whether Rutter’s indicators of adversity (low social class, severe marital discord, large family size, paternal criminality, maternal mental disorder, and placement in out-of-home care) assessed in infancy could serve as early predictors for the development of ADHD.

Methods and Findings

Using data from the Danish nationwide population-based registers, we established a cohort consisting of all 994,407 children born in Denmark between January 1^st 1993 and December 31^st 2011 and extracted dichotomous values for the six Rutter’s indicators of adversity at age 0–12 months (infancy) for each cohort member. The cohort members were followed from their second birthday and the association between the sum of Rutter’s indicators of adversity (RIA-score) in infancy and subsequent development of ADHD was estimated by means of Cox regression. Also, the number needed to screen (NNS) to detect one case of ADHD based on the RIA-scores in infancy was calculated. During follow-up (9.6 million person-years), 15,857 males and 5,663 females from the cohort developed ADHD. For both males and females, there was a marked dose-response relationship between RIA-scores assessed in infancy and the risk for developing ADHD. The hazard ratios for ADHD were 11.0 (95%CI: 8.2–14.7) and 11.4 (95%CI: 7.1–18.3) respectively, for males and females with RIA-scores of 5–6, compared to males and females with RIA-scores of 0. Among males with RIA-scores of 5–6, 37.6% (95%CI: 27.0–50.7) had been diagnosed with ADHD prior to the age of 20, corresponding to a NNS of 3.0 (95%CI: 2.2–4.0).

Conclusions

Rutter’s indicators of adversity assessed in infancy strongly predicted ADHD. This knowledge may be important for early identification of ADHD.