The effects of gender and age on repetitive and/or restricted behaviors and interests in adults with autism spectrum disorders and intellectual disability

Sex differences during development in cortical temporal processing and event related potentials in wild-type and fragile X syndrome model mice

BACKGROUND

Autism spectrum disorder (ASD) is currently diagnosed in approximately 1 in 44 children in the United States, based on a wide array of symptoms, including sensory dysfunction and abnormal language development. Boys are diagnosed ~ 3.8 times more frequently than girls. Auditory temporal processing is crucial for speech recognition and language development. Abnormal development of temporal processing may account for ASD language impairments. Sex differences in the development of temporal processing may underlie the differences in language outcomes in male and female children with ASD. To understand mechanisms of potential sex differences in temporal processing requires a preclinical model. However, there are no studies that have addressed sex differences in temporal processing across development in any animal model of ASD.

METHODS

To fill this major gap, we compared the development of auditory temporal processing in male and female wildtype (WT) and Fmr1 knock-out (KO) mice, a model of Fragile X Syndrome (FXS), a leading genetic cause of ASD-associated behaviors. Using epidural screw electrodes, we recorded auditory event related potentials (ERP) and auditory temporal processing with a gap-in-noise auditory steady state response (ASSR) paradigm at young (postnatal (p)21 and p30) and adult (p60) ages from both auditory and frontal cortices of awake, freely moving mice.

RESULTS

The results show that ERP amplitudes were enhanced in both sexes of Fmr1 KO mice across development compared to WT counterparts, with greater enhancement in adult female than adult male KO mice. Gap-ASSR deficits were seen in the frontal, but not auditory, cortex in early development (p21) in female KO mice. Unlike male KO mice, female KO mice show WT-like temporal processing at p30. There were no temporal processing deficits in the adult mice of both sexes.

CONCLUSIONS

These results show a sex difference in the developmental trajectories of temporal processing and hypersensitive responses in Fmr1 KO mice. Male KO mice show slower maturation of temporal processing than females. Female KO mice show stronger hypersensitive responses than males later in development. The differences in maturation rates of temporal processing and hypersensitive responses during various critical periods of development may lead to sex differences in language function, arousal and anxiety in FXS.

Perceived misdiagnosis of psychiatric conditions in autistic adults

Background

Many autistic people, particularly women, do not receive an autism diagnosis until adulthood, delaying their access to timely support and clinical care. One possible explanation is that autistic traits may initially be misinterpreted as symptoms of other psychiatric conditions, leading some individuals to experience misdiagnosis of other psychiatric conditions prior to their autism diagnosis. However, little is currently known about the frequency and nature of psychiatric misdiagnoses in autistic adults.

Methods

Using data collected in the first half of 2019 from an ongoing longitudinal register of autistic adults in the Netherlands, this study explored the frequency of perceived psychiatric misdiagnoses before receiving an autism diagnosis. Gender differences were also explored. A sample of 1211 autistic adults (52.6% women, mean age 42.3 years), the majority of whom were Dutch and relatively highly educated, was evaluated.

Findings

Results showed that 24.6% (n = 298) of participants reported at least one previous psychiatric diagnosis that was perceived as a misdiagnosis. Personality disorders were the most frequent perceived misdiagnoses, followed by anxiety disorders, mood disorders, chronic fatigue syndrome/burnout-related disorders, and attention-deficit/hyperactivity disorder. Autistic women (31.7%) reported perceived misdiagnoses more frequently than men (16.7%). Women were specifically more likely than men to report perceived misdiagnoses of personality disorders, anxiety disorders, and mood disorders. Women also reported prior psychiatric diagnoses more often in general (65.8% versus 34.2% in men). Within the group of individuals with a prior diagnosis, perceived misdiagnoses were equally likely for men and women.

Interpretation

One in four autistic adults, and one in three autistic women, reported at least one psychiatric diagnosis, obtained prior to being diagnosed with autism, that was perceived as a misdiagnosis. Inaccurate diagnoses are linked to long diagnostic pathways and delayed recognition of autism. These findings highlight the need for improved training of mental health practitioners, in order to improve their awareness of the presentation of autism in adulthood and of the complex relationship between autism and co-occurring conditions. The current study constitutes a first step towards showing that autistic adults, and particularly women, may be at greater risk of experiencing misdiagnoses. Future studies based on larger, more representative samples are required, to replicate current findings and provide more reliable estimates of the overall frequency of misdiagnoses as well as the frequency of misdiagnoses for specific psychiatric conditions.

Funding

This study was made possible by funding from the Netherlands Organisation for Health Research and Development (ZonMW), project number 60-63600-98-834.

Sex-specific behavioural deficits in adulthood following acute activation of the GABAA receptor in the neonatal mouse

INTRODUCTION

Sex differences exist in the prevalence of neurodevelopmental disorders (NDDs). Part of the aetiology of NDDs has been proposed to be alterations in the balance between excitatory and inhibitory neurotransmission, leading to the question of whether males and females respond differently to altered neurotransmitter balance. We investigated whether pharmacological alteration of GABAA signalling in early development results in sex-dependent changes in adult behaviours associated with NDDs.

METHODS

Male and female C57BL/6J mice received intraperitoneal injections of 0.5mg/kg muscimol or saline on postnatal days (P) 3-5 and were subjected to behavioural testing, specifically open field, light dark box, marble burying, sucralose preference, social interaction and olfactory habituation/dishabituation tests between P60-90.

RESULTS

Early postnatal administration of muscimol resulted in reduced anxiety in the light dark box test in both male and female adult mice. Muscimol reduced sucralose preference in males, but not females, whereas female mice showed reduced social behaviours. Regional alterations in cortical thickness were observed in the weeks following GABAA receptor activation, pointing to an evolving structural difference in the brain underlying adult behaviour.

CONCLUSIONS

We conclude that activation of the GABAA receptor in the first week of life resulted in long-lasting changes in a range of behaviours in adulthood following altered neurodevelopment. Sex of the individual affected the nature and severity of these abnormalities, explaining part of the varied pathophysiology and neurodevelopmental diagnosis that derive from excitatory/inhibitory imbalance.

Research Review: A systematic review and meta-analysis of sex differences in narrow constructs of restricted and repetitive behaviours and interests in autistic children, adolescents, and adults

BACKGROUND

Evidence that autism often manifests differently between males and females is growing, particularly in terms of social interaction and communication, but it is unclear if there are sex differences in restricted and repetitive behaviours and interests (RRBIs) when rigorously focusing on the narrow construct level (i.e., stereotyped behaviour, restricted interests, insistence on sameness, and/or sensory experiences).

METHODS

We conducted a systematic review and four random effects meta-analyses investigating sex differences in narrow construct measures of RRBIs in autistic children, adolescents, and adults (Prospero registration ID: CRD42021254221). Study quality was appraised using the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

Forty-six studies were narratively synthesised and 25 of these were included in four random effects meta-analyses. Results found that autistic males had significantly higher levels of stereotyped behaviours (SMD = 0.21, 95% confidence interval (CI) [0.09, 0.33], p < .001) and restricted interests (SMD = 0.18, 95% CI [0.07, 0.29], p < .001) compared to autistic females. In contrast, there were no significant sex differences for sensory experiences (SMD = -0.09, 95% CI [-0.27, 0.09], p = .32) and insistence on sameness (SMD = 0.01, 95% CI [-0.03, 0.05], p = .68). The findings from the narrative synthesis were generally consistent with those from the meta-analyses and also found qualitative sex differences in the way RRBIs manifest.

CONCLUSIONS

Our findings show significant differences in narrowly defined RRBIs in males and females. Practitioners need to be aware of such differences, which could be contributing to the under-recognition of autism in females and may not be captured by current diagnostic instruments.

Barriers to an Autistic Identity: How RRBs may Contribute to the Underdiagnosis of Females

Background

Autistic females are frequently underdiagnosed, misdiagnosed, and/or diagnosed later in life. Restricted and Repetitive Behaviors (RRBs) are increasingly critical for diagnosis and yet are commonly rated lower in females. Whether this reflects genuinely lower levels of these traits, or if female-typical RRBs have a different phenotypic presentation that may not register on current quantitative measurement tools is unclear.

Methods

Twenty-one autistic females and 21 autistic males matched on chronological age and FSIQ completed the AQ, ADOS-2, and ADI-R. Items from the ADOS-2 and ADI-R were selected that were relevant to the four areas of restricted and repetitive behavior in the DSM-5 diagnostic criteria of autism. Using a mixed-methods analytical approach, scores and comments on these measures were compared between sexes to better characterize RRBs in autistic females.

Results

There were no sex differences on the AQ, which broadly assesses autistic traits. When analyzed by the four DSM-5 RRB criteria, there were no sex differences on the ADI-R when using traditional algorithm scoring that narrows questions down to those that are more sensitive and specific in capturing autism in research samples with a high proportion of males. When incorporating additional items relevant to the DSM-5 to identify sex changes in a broader pool of items, females scored higher on stereotyped movements and speech. Females also engaged in more sensory behaviors during the ADOS-2. Qualitative analyses indicated that females were more likely to engage in stereotyped body rocking and spinning, stereotyped behaviors when anxious, to show major reactions to changes, repetitive language including listing and counting, and sensory behaviors, especially in the tactile domain.

Conclusion

Exploratory findings highlight sex differences in RRBs that may help enhance diagnostic clarity for females. Higher tactile sensory behaviors in females suggests there may be increased diagnostic sensitivity for females with the updated DSM-5 that now includes sensory components as part of the diagnostic criteria.

Exploring the intersection of autism spectrum disorder and eating disorders: understanding the unique challenges and treatment considerations for autistic women with eating disorders

PURPOSE OF REVIEW

Autistic women struggle with high levels of both autistic eating behaviours and disordered eating behaviours , which might make them particularly vulnerable to develop eating disorders. Research investigating the presence and characteristics of eating disorders in autistic women is however limited, as is research examining the role of autism in the treatment and recovery of an eating disorder in autistic women.

RECENT FINDINGS

The link between autism and eating disorders has mainly been investigated from the field of eating disorder research, with studies finding an overrepresentation of autism or autistic traits in eating disorders populations. Findings also suggest that autism or autistic traits are associated with a more serious presentation of the eating disorders, including a higher chance of a chronic course of the eating disorders. Most studies however lack comprehensive autism assessments, making it difficult to determine the actual prevalence of autism and its role in women with eating disorders.

SUMMARY

Autistic women with an eating disorder seem to suffer from more complex eating disorders and seem to not benefit from current treatment modalities. This could be partly related to specific autism characteristics such as sensory sensitivities, which are not being considered by current treatment protocols. Future research needs to shed light on what underlies the eating behaviours of autistic women with an eating disorder, in order to help to adapt current treatment modalities to meet the unique needs of these women.

National screening for Egyptian children aged 1 year up to 12 years at high risk of Autism and its determinants: a step for determining what ASD surveillance needs

This study aimed to provide a national estimate of the prevalence of the high risk of autism spectrum disorder (ASD) and their determinants. A national screening survey was conducted for 41,640 Egyptian children aged 1 to 12 years in two phases. Tools used were Vineland's Adaptive Behavior Scales, Modified Checklist for Autism in Toddlers, Gilliam Autism Rating scale, and Denver II Developmental screening test. The overall prevalence of children at high risk of ASD was 3.3% (95% CI:3.1%-3.5%). Children living without mothers in homes, suffered from convulsions (AOR = 3.67; 95%CI:2.8-4.8), a history of cyanosis after birth (AOR = 1.87; 95% CI:1.35-2.59) or history of LBW babies (AOR = 1.53; 95% CI:1.23-1.89) carried higher odds of being at high risk of ASD.

National screening for Egyptian children aged 1 year up to 12 years at high risk of Autism and its determinants: a step for determining what ASD surveillance needs

This study aimed to provide a national estimate of the prevalence of the high risk of autism spectrum disorder (ASD) and their determinants. A national screening survey was conducted for 41,640 Egyptian children aged 1 to 12 years in two phases. Tools used were Vineland's Adaptive Behavior Scales, Modified Checklist for Autism in Toddlers, Gilliam Autism Rating scale, and Denver II Developmental screening test. The overall prevalence of children at high risk of ASD was 3.3% (95% CI:3.1%–3.5%). Children living without mothers in homes, suffered from convulsions (AOR = 3.67; 95%CI:2.8–4.8), a history of cyanosis after birth (AOR = 1.87; 95% CI:1.35–2.59) or history of LBW babies (AOR = 1.53; 95% CI:1.23–1.89) carried higher odds of being at high risk of ASD.

Sex Differences in the Developmental Trajectories of Autism Spectrum Disorder

Purpose of Review

Females and males are disproportionately diagnosed with autism, a sex difference that has historically represented this neurodevelopmental condition. The current review examines lifespan developmental trajectories of autism based on sex to elucidate behavioral phenotypic differences that may contribute to differential rates of diagnosis.

Recent Findings

We review sex differences in diagnostic criteria: social communication and restricted interests/repetitive behaviors (RRBs). Results suggest RRBs are more indicative of a diagnosis in males, whereas social differences are more indicative of a diagnosis in females. Factors contributing to a later diagnosis in females include social strengths (camouflaging) and diagnostic overshadowing.

Summary

Sex differences in diagnostic criteria may contribute to differential rates of identification in males and females. Sex differences are most pronounced when assessing naturalistic social communication instead of reliance on standardized measure. Numerous future directions are identified including increasing samples of sub-threshold autistic females and evaluating longitudinal sex differences.

Intellectual disabilities moderate sex/gender differences in autism spectrum disorder: a systematic review and meta-analysis

BACKGROUND

Girls/women with autism spectrum disorder (ASD) are suggested to exhibit different symptom profiles than boys/men with ASD. Accumulating evidence suggests that intellectual disability (ID) may affect sex/gender differences in ASD. However, a systematic review and meta-analysis on this topic is missing.

METHODS

Two databases (MEDLINE and PsycINFO) were used to search for studies reporting sex/gender differences (girls/women versus boys/men) in social communication and interaction, restrictive and repetitive behaviour and interests (RRBIs), sensory processing, and linguistic and motor abilities in ASD. The final sample consisted of 79 studies. The meta-analysis was performed with Review Manager using a random-effects model. Participants with ASD without and with ID were analysed as separate subgroups, and the effects in these two subgroups were also compared with each other.

RESULTS

Girls/women with ASD without ID displayed fewer RRBIs, more sensory symptoms and less problems in linguistic abilities than their boys/men counterparts. In contrast, girls/women with ASD with ID displayed more social difficulties and RRBIs, poorer linguistic abilities and more motor problems than boys/men with ASD with ID. Comparisons of groups of participants with ASD without ID versus participants with ASD with ID confirmed differences in sex/gender effects on social difficulties, sensory processing, linguistic abilities and motor abilities.

CONCLUSIONS

Our results clearly suggest that the female phenotype of ASD is moderated by ID. Among individuals with ASD with ID, girls/women seem to be more severely affected than boys/men, whereas among individuals with ASD without ID, girls/women with ASD may have less symptoms than boys/men. Such phenotypic differences could be a potential cause of underrecognition of girls/women with ASD, and it is also possible that observed phenotypic differences may reflect underdiagnosing of girls/women with ASD.

Virtual and Augmented Reality in Social Skills Interventions for Individuals with Autism Spectrum Disorder: A Scoping Review

In the last decade, there has been an increase in publications on technology-based interventions for autism spectrum disorder (ASD). Virtual reality based assessments and intervention tools are promising and have shown to be acceptable amongst individuals with ASD. This scoping review reports on 49 studies utilizing virtual reality and augmented reality technology in social skills interventions for individuals with ASD. The included studies mostly targeted children and adolescents, but few targeted very young children or adults. Our findings show that the mode number of participants with ASD is low, and that female participants are underrepresented. Our review suggests that there is need for studies that apply virtual and augmented realty with more rigorous designs involving established and evidenced-based intervention strategies.

Visual and social differences in dyslexia: deep phenotyping of four cases with spared phonology

Diagnostic criteria for dyslexia describe specific reading difficulties, and single-deficit models, including the phonological deficit theory, have prevailed. Children seeking diagnosis, however, do not always show phonological deficits, and may present with strengths and challenges beyond reading. Through extensive neurological, neuropsychological, and academic evaluation, we describe four children with visuospatial, socio-emotional, and attention impairments and spared phonology, alongside long-standing reading difficulties. Diffusion tensor imaging revealed white matter alterations in inferior longitudinal, uncinate, and superior longitudinal fasciculi versus neurotypical children. Findings emphasize that difficulties may extend beyond reading in dyslexia and underscore the value of deep phenotyping in learning disabilities.

The Diagnosis and Management of Autism Spectrum Disorder (ASD) in Adult Females in the Presence or Absence of an Intellectual Disability

We review the reasons for the greater male predominance in the diagnosis of autism spectrum disorder in the non-intellectual disabled population and compare it to autism diagnosed in intellectually disabled individuals. Accurate and timely diagnosis is important, as it reduces health inequalities. Females often present later for the diagnosis. The differences are in core features, such as in social reciprocal interaction through 'camouflaging' and restricted repetitive behaviours, that are less noticeable in females and are potentially explained by the biological differences (female protective effect theory) and/or differences in presentation between the two sexes (female autism phenotype theory). Females more often present with internalising co-occurring conditions than males. We review these theories, highlighting the key differences and the impact of a diagnosis on females. We review methods to potentially improve diagnosis in females along with current and future management strategies.

Exploring Cultural Differences in Autistic Traits: A Factor Analytic Study of Children with Autism in China and the Netherlands

Autism spectrum disorders are diagnosed globally, but recognition, interpretation and reporting may vary across cultures. To compare autism across cultures it is important to investigate whether the tools used are conceptually equivalent across cultures. This study evaluated the factor structure of the parent-reported Autism Spectrum Quotient Short Form in autistic children from China (n = 327; 3 to 17 years) and the Netherlands (n = 694; 6 to 16 years). Confirmatory factor analysis did not support the two-factor hierarchical model previously identified. Exploratory factor analysis indicated culturally variant factor structures between China and the Netherlands, which may hamper cross-cultural comparisons. Several items loaded onto different factors in the two samples, indicating substantial variation in parent-reported autistic traits between China and the Netherlands.

Autistic adults' subjective experiences of hoarding and self-injurious behaviors

LAY ABSTRACT

Hoarding and self-injurious behaviors are relatively common in autism, but knowledge about their expressions in adulthood is scarce. Through interviews collecting subjective experiences of autistic adults, these behaviors were explored, and categorized to their underlying purposes. Findings portray the occurrence of these behaviors in the lives of autistic adults, their self-regulatory purposes, and their relationship to other behaviors in the domain of Restrictive and Repetitive Behaviors and Interests.

Age differences in broader autism phenotype traits from young adulthood to older adulthood

Much of past research has been dedicated to refining the operationalization and correlates of the broader autism phenotype (BAP) and less on how the BAP differs by socio-demographic characteristics, like age-particularly after midlife. This gap is important because other nonclinical trait-like characteristics (e.g., personality) have shown considerable age differences, leading to work assessing the malleability of psychological characteristics and improving outcomes for individuals and their significant others. In the current study, we examined cross-sectional age differences in the BAP in a large sample of adults ranging in age from 18 to 85. We recruited a sample of 2966 adults ranging in age from 18 to 85 (M_age = 36.53, SD = 12.61; 58.9% Female; 1.1% with an ASD diagnosis) recruited from an online survey service. We found that total BAP scores were higher in younger adults and lower among older adults. These differences were particularly true for pragmatic language difficulties, with this component of the BAP showing the most dramatic age differences. Aloofness showed similar negative associations with age, albeit much smaller. Rigidity was not significantly associated with age. The results are consistent with other research showing an abatement of symptoms among individuals with autism spectrum disorders (ASDs) across early life and theories predicting changes in other psychological characteristics (e.g., personality). The results are discussed in the context of the malleability of ASD and BAP traits across life, the clinical implications of these changes, and the origins and consequences for lifespan differences in BAP. LAY SUMMARY: Little is known about how subclinical autistic-like traits among middle-aged and older adults compare to younger adults. We found that these subclinical traits were highest in young adults and lowest in older adults. Knowing how these traits differ by age can provide researchers and clinicians with a sense of how much these traits might change across life, if the traits might be sensitive to interventions, and when in development it might be best to intervene.

The effects of oxytocin administration on individuals with ASD: Neuroimaging and behavioral evidence

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by difficulties in social communication and the presence of restricted interests and repetitive behaviors. Although behavioral interventions are numerous, there are no Federal Drug Administration approved pharmacological treatments for the core symptoms of ASD. The neuropeptide oxytocin has been studied in animals for decades, and is involved in pair bonding and social affiliation. Given oxytocin's involvement in social communication in animals, researchers have begun exploring whether oxytocin administration in humans affects social behaviors and attachment. Particular attention has been paid to whether oxytocin has therapeutic benefits for improving social behaviors in individuals with ASD. Research on oxytocin administration in ASD has utilized both behavioral and brain-based outcomes. This chapter reviews the effects of oxytocin administration in ASD, with a focus on functional outcomes from neuroimaging investigations. Evidence of potential therapeutic benefits are reviewed, as well as limitations of extant research. A proposed model for future research into the therapeutic benefits of oxytocin includes combining pharmacological (e.g. oxytocin) and behavioral (e.g. evidence-based behavioral interventions) techniques to improve social communication skills in ASD.

Differences in Developmental Functioning Profiles Between Male and Female Preschoolers Children With Autism Spectrum Disorder

This study investigated differences in clinical symptoms and developmental functioning profiles as well as sex-specific correlations of clinical characteristics and communication abilities, motor skills, and maladaptive behaviors in male and female preschoolers with autism spectrum disorder (ASD). Fifty-two females (mean age 4.5 ± 2.16 years old) and 62 males (mean age 4.2 ± 1.17 years old) with ASD were enrolled and assessed by measures including the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2) and Psychoeducational Profile-Third Edition (PEP-3). We found intellectual disability in 91.2% of the children. While preschoolers with ASD showed comparable severity of restricted and repetitive behaviors (P = 0.17), females with ASD were less severely affected than age and intelligence quotient-matched males with ASD in the ADOS-2 social affect domain (P value = 0.001) and calibrated severity scores (P = 0.002). Interestingly, sex-specific linear regressions revealed that fine motor skills were predictive of impaired social affect in males but not in females. Specifically, motor skills might be the core feature for sex differences in ASD. Although preliminary, this finding suggests the need for more sex-specific diagnostic and intervention strategies in order to improve early identification efforts and specific intervention targets. LAY SUMMARY: Little is known about differences in developmental and functional profiles in males and females with autism spectrum disorder (ASD). We found important similarities and differences in the core ASD symptoms between male and female preschoolers. In addition, fine motor skills seem to predict social affect impairment and ASD symptom severity in males with ASD. Autism Res 2020, 13: 1537-1547. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.

Bacterial-induced maternal interleukin-17A pathway promotes autistic-like behaviors in mouse offspring

Maternal immune activation (MIA) by an infection is considered to be an important environmental factor of fetal brain development. Recent animal model on MIA induced by polyinosinic:polycytidylic acid, a mimic of viral infection, demonstrates that maternal IL-17A signaling is required for the development of autism spectrum disorder (ASD)-like behaviors of offspring. However, there is little information on bacterial infection. In this study, we aim to elucidate the influence of MIA induced by lipopolysaccharide (LPS) to mimic a bacterial infection on fetal brain development. We demonstrated that LPS-induced MIA promoted ASD-like behaviors in mouse offspring. We further found that LPS exposure induced acute phase immune response: elevation of serum IL-17A levels in MIA mothers, upregulation of Il17a mRNA expression and increase of IL-17A-producing γδ T cells in the uterus, and upregulation of Il17ra mRNA expression in the fetal brain. Blocking of IL-17A in LPS-induced MIA ameliorated ASD-like behaviors in offspring. Our data suggest that bacterial-induced maternal IL-17A pathway promotes ASD-like behaviors in offspring.

The Female Autism Phenotype and Camouflaging: a Narrative Review

Autism is more commonly diagnosed in males than females. One explanation is the ‘female protective effect’: there is something inherent in being female which reduces the likelihood of developing autism. However, evidence suggests that the condition is underdiagnosed in females, perhaps because females express their autism in ways which do not meet current diagnostic criteria. This review explores evidence for a female-typical autism presentation, the Female Autism Phenotype (FAP) and the component of camouflaging (compensating for and masking autistic characteristics) in particular. The evidence so far supports the existence of a female-typical autism presentation, although further examination of the characteristics and their impact across all genders and ages is needed.

Sex Differences in Social Adaptive Function in Autism Spectrum Disorder and Attention-Deficit Hyperactivity Disorder

Background: Social-communication difficulties, a hallmark of ASD, autism spectrum disorder (ASD) are often observed in attention - deficit/ hyperactivity disorder (ADHD), although are not part of its diagnostic criteria. Despite sex differences in the prevalence of ASD and ADHD, research examining how sex differences manifest in social and communication functions in these disorders remains limited, and findings are mixed. This study investigated potential sex differences with age in social adaptive function across these disorders, relative to controls. Method: One hundred fifteen youth with ASD, 172 youth with ADHD, and 63 typically developing controls (age range 7-13 years, 75% males) were recruited from the Province of Ontario Neurodevelopmental Disorder (POND) Network. Social adaptive function was assessed using the Adaptive Behavior Assessment System-Second Edition (ABAS-II). The proportions of adaptive behaviors present in each skill area were analyzed as a binomial outcome using logistic regression, controlling for age, and testing for an age-by-sex interaction. In an exploratory analysis, we examined the impact of controlling for core symptom severity on the sex effect. Results: Significant sex-by-age interactions were seen within ASD in the communication (p = 0.005), leisure (p = 0.003), and social skill areas (p < 0.0001). In all three areas, lower scores (indicating poorer function) were found in females compared to males at older ages despite females performing better at younger ages. There were significant differences in the sex-by-age interactions in the social and leisure domains between those with ASD and typically developing controls, with typically developing females showing better scores at older, compared to younger, ages. There were also significant differences in the sex-by-age interactions between ASD and ADHD on the social and leisure domains, as females with ADHD consistently scored higher on social skills than males across all ages, unlike those with ASD. Sex differences across age in the social domains for ADHD were similar to those in the typically developing group. Conclusion: Sex differences in social and communication skill areas were observed between ASD and ADHD, and typically developing controls, with females with ASD performing worse than males at older ages, despite an earlier advantage. These findings reinforce the need to take a developmental approach to understanding sex differences which may have diagnostic, prognostic, and treatment implications.

Sex-Differences in Children Referred for Assessment: An Exploratory Analysis of the Autism Mental Status Exam (AMSE)

The autism mental status exam is an eight-item observational assessment that structures the way we observe and document signs and symptoms of ASD. Investigations of test performance indicate strong sensitivity and specificity using gold-standard assessment as reference standard. This study aims to explore potential sex differences in AMSE test performance and observations of 123 children referred for autism assessment. Results indicates more language deficits in females with ASD than in males with ASD and less sensory symptoms in females compared to males with ASD. The AMSE performance is similar in identifying ASD and non-ASD in females compared to males. Less disruptive behaviors in females, might cause a need for a bigger hit to other areas of development to raise concern.

Exploring the female autism phenotype of repetitive behaviours and restricted interests (RBRIs): a systematic PRISMA review

Purpose

The purpose of this paper is to address the need for increased understanding, awareness and recognition of the autism female phenotype in terms of repetitive behaviours and restricted interests (RBRIs).

Design/methodology/approach

A systematic PRISMA review was conducted. The main aim of the present systematic review is to identify studies which have investigated RBRIs in females with autism spectrum disorder (ASD) or the differences in RBRIs between males and females with ASD.

Findings

In sum, 19 relevant articles were identified: 5 studies found no significant evidence to support the notion of sex differences in RRBIs in ASD; 1 study did not report any differences in RRBIs between males and females with ASD; 12 studies found evidence that males with ASD had significantly more RRBIs compared to females with ASD; and, lastly, 1 study found that girls with ASD have features of RRBIs which are exhibited more compared to boys with ASD.

Research limitations/implications

There is a real lack of in-depth knowledge and understanding of the female phenotype of ASD, and such lack of knowledge has a detrimental impact on the identification of autistic females and a lack of identification can have negative consequence. This is important to address in future research as it is well established that the earlier the diagnosis, the better the outcomes, due to the timely access to appropriate interventions.

Practical implications

The RBRIs exhibited in autistic females are not sufficiently captured by most currently diagnostic instruments. Clinicians are less likely to identify the RBRIs in females as they tend not to be the typical repetitive behaviours commonly associated with ASD. It has been recommended that clinicians consider “females as a whole” in terms of their clinical presentation and look for any indication of RBRIs, even repetitive interests which appear clinically innocuous.

Originality/value

There is relatively little research investigating RBRIs in autistic women and girls. There is a real need to highlight the importance of understanding and recognising how RBRIs can differ between males and females with ASD.

Increased facial asymmetry in autism spectrum conditions is associated with symptom presentation

A key research priority in the study of autism spectrum conditions (ASC) is the discovery of biological markers that may help to identify and elucidate etiologically distinct subgroups. One physical marker that has received increasing research attention is facial structure. Although there remains little consensus in the field, findings relating to greater facial asymmetry (FA) in ASC exhibit some consistency. As there is growing recognition of the importance of replicatory studies in ASC research, the aim of this study was to investigate the replicability of increased FA in autistic children compared to nonautistic peers. Using three-dimensional photogrammetry, this study examined FA in 84 autistic children, 110 typically developing children with no family history of the condition, and 49 full siblings of autistic children. In support of previous literature, significantly greater depth-wise FA was identified in autistic children relative to the two comparison groups. As a further investigation, increased lateral FA in autistic children was found to be associated with greater severity of ASC symptoms on the Autism Diagnostic Observation Schedule, second edition, specifically related to repetitive and restrictive behaviors. These outcomes provide an important and independent replication of increased FA in ASC, as well as a novel contribution to the field. Having confirmed the direction and areas of increased FA in ASC, these findings could motivate a search for potential underlying brain dysmorphogenesis. Autism Res 2019, 12: 1774-1783. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This study looked at the amount of facial asymmetry (FA) in autistic children compared to typically developing children and children who have siblings with autism. The study found that autistic children, compared to the other two groups, had greater FA, and that increased FA was related to greater severity of autistic symptoms. The face and brain grow together during the earliest stages of development, and so findings of facial differences in autism might inform future studies of early brain differences associated with the condition.

Neurological Diseases With Autism Spectrum Disorder: Role of ASD Risk Genes

Autism spectrum disorder (ASD) is frequently comorbid with other neurological disorders such as intellectual disability (ID) or global development delay (GDD) and epilepsy. The pathogenesis of ASD is complex. So far, studies have identified more than 1000 ASD risk genes. Most of them were also reported to relate with other neurological diseases, and only several of them have been confirmed as pathogenic genes for autism. Little is known about the roles of these risk genes in neurological diseases with ASD. In the present study, we recruited a cohort of 158 neurological disorder probands with 163 variants of 48 ASD risk genes. Of these, 50 individuals (31.6%) were diagnosed with ASD. In the ASD patient subset, we identified several rarely reported candidate genes including DOLK, USH2A, and HUWE1. In a comparison of patients with neurological disorders with and without ASD, we found that ID/GDD was frequently comorbid with ASD whereas epilepsy was more common in the non-ASD group. Statistical analyses of all possible risk factors implicated that variants in synaptic genes, especially non-voltage-gated ion channel genes and in transcriptional and chromosome genes were related to ASD, but none of the investigated environmental factors was. Our results are useful for the future diagnosis and prognosis of patients with neurological disorders and emphasize the utility of genetic screening.

Annual trends in prevalence and incidence of autism spectrum disorders in Manitoba preschoolers and toddlers: 2004-2015

OBJECTIVES

Autism spectrum disorders (ASD) are among the leading causes of disabilities in children. We examined the annual prevalence and incidence rate of ASD between 2004 and 2015 in children aged 1 to 5 years residing in Manitoba.

METHODS

A population-based study was conducted using the Manitoba Population Research Data Repository. The study included children aged 1 to 5 years residing in Manitoba between 2004 and 2015. Standard identification algorithm was used to identify ASD cases from hospital abstracts and medical claims. Annual prevalence and incidence rates were calculated for the overall population and then stratified according to sex, region, and socio-economic status (SES). Multivariable negative binomial regression models, adjusted for sex, region, and SES, were used to examine changes in prevalence and incidence over study years.

RESULTS

Among children aged 1 to 5 years, 1685 ASD cases were diagnosed between 2004 and 2015. The crude ASD prevalence increased from 0.46% in 2004 to 0.97% in 2015 (p = 0.002). The crude incidence rate increased from 0.16% in 2004 to 0.39% in 2015 (p = 0.002). The increase in ASD prevalence and incidence was observed in all subgroups based on sex, region, and SES. The adjusted negative binomial model showed an annual relative risk increase, since 2004, for both prevalence and incidence of 1.69 (95% CI 1.56-1.83) and 1.84 (95% CI 1.62-2.09), respectively.

CONCLUSION

During the period from 2004 to 2015, both prevalence and incidence rates of diagnosed ASD in preschoolers and toddlers residing in Manitoba increased significantly.

Gender differences in restricted and repetitive behaviors and interests in youth with autism

Previous work has found gender differences in restricted and repetitive behaviors and interests (RRBI) for autism spectrum disorder (ASD). Compared to girls, affected boys have increased stereotyped and restricted behaviors; however much less is known about gender differences in other areas of RRBI. This study aims to identify whether specific RRBI (i.e., stereotyped, self-injurious, compulsive, insistence on sameness, ritualistic, and restricted), as measured by item-level data on the Repetitive Behavior Scale-Revised (RBS-R), can distinguish girls from boys with ASD. Participants included 615 individuals with ASD (507 boys; 82.4%), ages 3-18 years of age (M = 10.26, SD = 4.20), who agreed to share data with the National Database for Autism Research (NDAR). Multivariate analysis of variance and discriminant function analysis (DFA) were used to determine whether item-level RBS-R data could correctly classify cases by gender. DFA results suggest that RBS-R items significantly differentiate gender. Strongly differentiating RBS-R items had greater success in correctly classifying affected boys (67.90%) than girls (61.00%). Items that best-discriminated gender were heightened stereotyped behaviors and restricted interests items in boys and compulsive, sameness, restricted, and self-injurious behavior items in girls. This study is the first to find that girls with ASD may have increased compulsive, sameness, and restricted RRBI compared to boys. Additionally, findings support heightened self-injurious behaviors in affected girls. Future research should disentangle whether elevated rates of RRBI in girls are central to the presentation of ASD in girls or an epiphenomenon of the high rates of co-occurring disorders (e.g., anxiety) noted in girls. Autism Res 2019, 12: 274-283 © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This study is the first to examine a comprehensive measure of repetitive behavior in children with autism, with findings of increased compulsive, insistence on sameness, and self-injurious behavior characterizing girls and increased stereotyped and restricted behavior characterizing boys. Future research should determine whether these elevated behaviors in girls are directly part of the autism presentation in girls or symptoms of co-occurring psychopathology. It is important for autism diagnostic measures to best capture the types of repetitive behavior girls may demonstrate.

Assessing subtypes of restricted and repetitive behaviour using the Adult Repetitive Behaviour Questionnaire-2 in autistic adults

Background

The majority of previous research into restricted and repetitive behaviours (RRBs) has focussed on children, partly due to a lack of suitable measures for RRBs in adults. This study aimed to explore the psychometric properties of the Adult Repetitive Behaviour Questionnaire-2 (RBQ-2A) in a large sample of autistic adults using a self-report questionnaire method.

Methods

The RBQ-2A and Autism-Spectrum Quotient (AQ) were administered online. Data from 275 autistic adults aged 18-66 (M = 36.56, SD = 12.24; 100 men and 171 women) were analysed using polychoric principal components analysis (PCA). Reliability and validity were assessed using Cronbach's alpha and correlation analyses.

Results

PCA resulted in two components of the RBQ-2A, interpretable as repetitive sensory and motor behaviours (RSMB) and insistence on sameness (IS). Both components showed acceptable internal consistency (α = .70 and .81 respectively) and were significantly moderately correlated with scores on the AQ (r _s  = .25 and .42). Participants' scores on IS were higher than their scores on RSMB. RSMB, but not IS, was negatively associated with age, particularly in older adults (≥ 50 years). There were no gender differences.

Conclusions

The RBQ-2A is a reliable and valid self-report measure of RRBs in the present sample of autistic adults. As one of the few measures of RRBs aimed at adults, it is suitable for adults with the ability to read and complete a self-report questionnaire. Results build on previous work with children using the Repetitive Behaviour Questionnaire-2 (RBQ-2).

Developmental neurogenetics and multimodal neuroimaging of sex differences in autism

Examining sex differences in the brain has been historically contentious but is nonetheless important for advancing mental health for both girls and boys. Unfortunately, females in biomedical research remain underrepresented in most mental health conditions including autism spectrum disorders (ASD), even though equal inclusion of females would improve treatment for girls and yield benefits to boys. This review examines sex differences in the relationship between neuroanatomy and neurogenetics of ASD. Recent findings reveal that girls diagnosed with ASD exhibit more intellectual and behavioral problems compared to their male counterparts, suggesting that girls may be less likely diagnosed in the absence of such problems or that they require a higher mutational load to meet the diagnostic criteria. Thus far, the female biased effect of chromosome 4, 5p15.33, 8p, 9p24.1, 11p12-13, 15q, and Xp22.3 and the male biased effect of 1p31.3, 5q12.3, 7q, 9q33.3, 11q13.4, 13q33.3, 16p11.2, 17q11-21, Xp22.33/Yp11.31, DRD1, NLGN3, MAOA, and SHANK1 deletion have been discovered in ASD. The SNPs of genes such as RYR2, UPP2, and the androgen receptor gene have been shown to have sex-biasing factors in both girls and boys diagnosed with ASD. These sex-related genetic factors may drive sex differences in the neuroanatomy of these girls and boys, including abnormal enlargement in temporal gray and white matter volumes, and atypical reduction in cerebellar gray matter volumes and corpus callosum fibers projecting to the anterior frontal cortex in ASD girls relative to boys. Such factors may also be responsible for the attenuation of brain sexual differentiation in adult men and women with ASD; however, much remains to be uncovered or replicated. Future research should leverage further the association between neuroanatomy and genetics in girls for an integrated and interdisciplinary understanding of ASD.

Psychometric Properties of Spanish Adaptation of the PDD-MRS Scale in Adults with Intellectual Developmental Disorders: The EVTEA-DI Scale

Strategies for the early detection of autism spectrum disorders (ASD) in people with intellectual developmental disorder (IDD) are urgently needed, but few specific tools have been developed. The present study examines the psychometric properties of the EVTEA-DI, a Spanish adaptation of the PDD-MRS, in a large randomized sample of 979 adults with IDD. Factorial solution analysis suggested a three-factor solution (stereotyped behavior, communication, and social behavior). The EVTEA-DI showed good reliability and convergent validity when compared to the Childhood Autism Rating Scale. Discriminative validity analysis resulted in an acceptable global sensitivity of 70% and a high specificity of 90%. The EVTEA-DI proved to be a valid screening tool in ASD assessment of the adult Spanish population with IDD.

Sex Differences in Diagnosis and Clinical Phenotypes of Chinese Children with Autism Spectrum Disorder

The aim of this study was to explore the differences between boys and girls in the diagnosis and clinical phenotypes of autism spectrum disorder (ASD) in China's mainland. Children diagnosed with ASD (n = 1064, 228 females) were retrospectively included in the analysis. All children were assessed using the Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedule (ADOS). The results showed that girls scored significantly higher in ADI-R socio-emotional reciprocity than boys, and also scored lower in ADI-R and ADOS restricted and repetitive behaviors (RRBs). Meanwhile, the proportions of girls who satisfied the diagnostic cut-off scores in the ADI-R RRBs domain were lower than in boys (P < 0.05). Our results indicated that girls with ASD show greater socio-emotional reciprocity than boys. Girls also tended to show fewer RRBs than boys, and the type of RRBs in girls differ from those in boys. The ADI-R was found to be less sensitive in girls, particularly for assessment in the RRBs domain.

Parent-Endorsed Sex Differences in Toddlers with and Without ASD: Utilizing the M-CHAT

Sex differences in typical development can provide context for understanding ASD. Baron-Cohen (Trends Cogn Sci 6(6):248-254, 2002) suggested ASD could be considered an extreme expression of normal male, compared to female, phenotypic profiles. In this paper, sex-specific M-CHAT scores from N = 53,728 18-month-old toddlers, including n = 185 (32 females) with ASD, were examined. Results suggest a nuanced view of the "extreme male brain theory of autism". At an item level, almost every male versus female disadvantage in the broader population was consistent with M-CHAT vulnerabilities in ASD. However, controlling for total M-CHAT failures, this male disadvantage was more equivocal and many classically ASD-associated features were found more common in non-ASD. Within ASD, females showed relative strengths in joint attention, but impairments in imitation.

Exploring sex differences in autistic traits: A factor analytic study of adults with autism

Research has highlighted potential differences in the phenotypic and clinical presentation of autism spectrum conditions across sex. Furthermore, the measures utilised to evaluate autism spectrum conditions may be biased towards the male autism phenotype. It is important to determine whether these instruments measure the autism phenotype consistently in autistic men and women. This study evaluated the factor structure of the Autism Spectrum Quotient Short Form in a large sample of autistic adults. It also systematically explored specific sex differences at the item level, to determine whether the scale assesses the autism phenotype equivalently across males and females. Factor analyses were conducted among 265 males and 285 females. A two-factor structure consisting of a social behaviour and numbers and patterns factor was consistent across groups, indicating that the latent autism phenotype is similar among both autistic men and women. Subtle differences were observed on two social behaviour item thresholds of the Autism Spectrum Quotient Short Form, with women reporting scores more in line with the scores expected in autism on these items than men. However, these differences were not substantial. This study showed that the Autism Spectrum Quotient Short Form detects autistic traits equivalently in males and females and is not biased towards the male autism phenotype.

Sex differences in neurodevelopmental and neurodegenerative disorders: Focus on microglial function and neuroinflammation during development

Several neurological conditions are associated with sex differences in prevalence or outcome. For example, autism predominantly affects boys, depression is more common in women, Parkinson's disease more common in men, and multiple sclerosis in women. In the case of stroke, women have a less favorable outcome and suffer from a more precipitous drop in health status compared to men. As a result, treatment of such diseases is difficult and yields variable results. Despite this, sex is rarely considered when making treatment decisions. The mechanisms underlying sex differences in disease progression are not well understood, however a strong link exists between different inflammation states of men and women and their propensity to develop certain diseases. As neuroinflammation is an important component of pathophysiology in many neurological conditions, it can be speculated that any changes in the state of inflammation in the brain during normal development can potentially lead to an increase in susceptibility to neurological and neurodegenerative diseases. Microglia play a crucial role in onset and modulation of inflammation and thus sex differences in microglial function could explain, at least in part, differences observed in susceptibilities and outcomes of neurological disorders in men and women. Understanding the mechanisms behind sex differences could help develop more targeted therapy with higher success rate, especially in diseases where sex differences are most prominent.

Retention of autism spectrum disorder diagnosis: The role of co-occurring conditions in males and females

This study examined associations between ASD diagnosis retention and non-ASD co-occurring conditions (CoCs) by child sex. The sample included 7077 males and 1487 females who had an ASD diagnosis documented in their school or health records in a population-based ASD surveillance system for 8-year-old children. ASD diagnosis retention status was determined when an initial ASD diagnosis was not later ruled out by a community professional. We found that ASD diagnosis remains fairly stable, with only 9% of children who had an initial documented ASD diagnosis later being ruled-out. Although most of the associations between the ASD diagnosis retention status and CoCs are similar in both sexes, the co-occurrence of developmental diagnoses (e.g., intellectual disability or sensory integration disorder) was predictive of ASD diagnostic changes in males, whereas the co-occurrence of specific developmental (e.g., personal/social delay) and neurological diagnosis (e.g., epilepsy) was associated with ASD diagnostic change in females. More ASD-related evaluations and less ASD-related impairment were associated with later ASD rule outs in both sexes. Our findings highlight that CoCs can complicate the diagnostic picture and lead to an increased likelihood of ambiguity in ASD diagnosis. Using sensitive and appropriate measures in clinical practice is necessary for differential diagnosis, particularly when there are co-occurring developmental conditions.

Autism and Overcoming Job Barriers: Comparing Job-Related Barriers and Possible Solutions in and outside of Autism-Specific Employment

The aim of this study was to discover how individuals with autism succeed in entering the job market. We therefore sought to identify expected and occurred barriers, keeping them from taking up and staying in employment as well as to identify the solutions used to overcome these barriers. Sixty-six employed individuals with autism--17 of them with autism-specific employment--participated in an online survey. Results showed a variety of possible barriers. Individuals in autism-specific employment named formality problems--problems with organizational and practical process-related aspects of the job entry--most frequently while individuals in non-autism-specific employment mentioned social problems--obstacles concerning communication and human interaction--most. In terms of solutions, both groups used their own resources as much as external help, but differed in their specific strategies. In addition, correlations of an autism-specific employment with general and occupational self-efficacy as well as life and job satisfaction were examined. Possible implications of the results are discussed with regard to problem solving behavior and the use of strengths.

Sex differences in structural organization of motor systems and their dissociable links with repetitive/restricted behaviors in children with autism

Background

Autism spectrum disorder (ASD) is diagnosed much less often in females than males. Emerging behavioral accounts suggest that the clinical presentation of autism is different in females and males, yet research examining sex differences in core symptoms of autism in affected children has been limited. Additionally, to date, there have been no systematic attempts to characterize neuroanatomical differences underlying the distinct behavioral profiles observed in girls and boys with ASD. This is in part because extant ASD studies have included a small number of girls.

Methods

Leveraging the National Database for Autism Research (NDAR), we first analyzed symptom severity in a large sample consisting of 128 ASD girls and 614 age- and IQ-matched ASD boys. We then examined symptom severity and structural imaging data using novel multivariate pattern analysis in a well-matched group of 25 ASD girls, 25 ASD boys, 19 typically developing (TD) girls, and 19 TD boys, obtained from the Autism Brain Imaging Data Exchange (ABIDE).

Results

In both the NDAR and ABIDE datasets, girls, compared to boys, with ASD showed less severe repetitive/restricted behaviors (RRBs) and comparable deficits in the social and communication domains. In the ABIDE imaging dataset, gray matter (GM) patterns in the motor cortex, supplementary motor area (SMA), cerebellum, fusiform gyrus, and amygdala accurately discriminated girls and boys with ASD. This sex difference pattern was specific to ASD as the GM in these brain regions did not discriminate TD girls and boys. Moreover, GM in the motor cortex, SMA, and crus 1 subdivision of the cerebellum was correlated with RRB in girls whereas GM in the right putamen—the region that discriminated TD girls and boys—was correlated with RRB in boys.

Conclusions

We found robust evidence for reduced levels of RRB in girls, compared to boys, with ASD, providing the strongest evidence to date for sex differences in a core phenotypic feature of childhood ASD. Sex differences in brain morphometry are prominent in the motor system and in areas that comprise the “social brain.” Notably, RRB severity is associated with sex differences in GM morphometry in distinct motor regions. Our findings provide novel insights into the neurobiology of sex differences in childhood autism.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-015-0042-z) contains supplementary material, which is available to authorized users.

Diagnosis and management of autism spectrum disorder in the era of genomics: rare disorders can pave the way for targeted treatments

Although the diagnosis of autism spectrum disorder (ASD) is based on behavioral signs and symptoms, the evaluation of a child with ASD has become increasingly focused on the identification of the genetic etiology of the disorder. In this review, we begin with a clinical overview of ASD, highlighting the heterogeneity of the disorder. We then discuss the genetics of ASD and present updated guidelines on genetic testing. We then consider the insights gained from the identification of both single gene disorders and rare variants, with regard to clinical phenomenology and potential treatment targets.

Sex differences in multisensory speech processing in both typically developing children and those on the autism spectrum

BACKGROUND

Previous work has revealed sizeable deficits in the abilities of children with an autism spectrum disorder (ASD) to integrate auditory and visual speech signals, with clear implications for social communication in this population. There is a strong male preponderance in ASD, with approximately four affected males for every female. The presence of sex differences in ASD symptoms suggests a sexual dimorphism in the ASD phenotype, and raises the question of whether this dimorphism extends to ASD traits in the neurotypical population. Here, we investigated possible sexual dimorphism in multisensory speech integration in both ASD and neurotypical individuals.

METHODS

We assessed whether males and females differed in their ability to benefit from visual speech when target words were presented under varying levels of signal-to-noise, in samples of neurotypical children and adults, and in children diagnosed with an ASD.

RESULTS

In typically developing (TD) children and children with ASD, females (n = 47 and n = 15, respectively) were significantly superior in their ability to recognize words under audiovisual listening conditions compared to males (n = 55 and n = 58, respectively). This sex difference was absent in our sample of neurotypical adults (n = 28 females; n = 28 males).

CONCLUSIONS

We propose that the development of audiovisual integration is delayed in male relative to female children, a delay that is also observed in ASD. In neurotypicals, these sex differences disappear in early adulthood when females approach their performance maximum and males "catch up." Our findings underline the importance of considering sex differences in the search for autism endophenotypes and strongly encourage increased efforts to study the underrepresented population of females within ASD.

A Review of the Differences in Developmental, Psychiatric, and Medical Endophenotypes Between Males and Females with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is over four times more prevalent in males compared to females. Increased understanding of sex differences in ASD endophenotypes could add insight into possible etiologies and the assessment and management of the disorder. Consequently, the purpose of this review is to describe current literature regarding sex differences in the developmental, psychiatric, and medical endophenotypes of ASD in order to illustrate current knowledge and areas in need of further research. Our review found that repetitive behaviors and restricted interests are more common in males than females with ASD. Intellectual disability is more common in females than males with ASD. Attention to detail may be more common in males than females with ASD and epilepsy may be more common in females than males with ASD, although limited research in these areas prevent definitive conclusions from being drawn. There does not appear to be a sex difference in other developmental, psychiatric, and medical symptoms associated with ASD, or the research was contradictory or too sparse to establish a sex difference. Our review is unique in that it offers detailed discussion of sex differences in three major endophenotypes of ASD. Further research is needed to better understand why sex differences exist in certain ASD traits and to evaluate whether phenotypic sex differences are related to different pathways of development, assessment, and treatment of the disorder.

Socialization and nonverbal communication in atypically developing infants and toddlers

Emphasis on early identification of atypical development has increased as evidence supporting the efficacy of intervention has grown. These increases have also directly affected the availability of funding and providers of early intervention services. A majority of research has focused on interventions specific to an individual's primary diagnoses. For example, interventions for those with cerebral palsy (CP) have traditionally focused on physiological symptoms, while intervention for individuals with Autism Spectrum Disorder (ASD) focus on socialization, communication, and restricted interests and repetitive behaviors. However deficits in areas other than those related to their primary diagnoses (e.g., communication, adaptive behaviors, and social skills) are prevalent in atypically developing populations and are significant predictors of quality of life. Therefore, the purpose of the current study was to examine impairments in socialization and nonverbal communication in individuals with Down's syndrome (DS), CP, and those with CP and comorbid ASD. Individuals with comorbid CP and ASD exhibited significantly greater impairments than any diagnostic group alone. However, individuals with CP also exhibited significantly greater impairments than those with DS. The implications of these results are discussed.

Gender and age differences in the core triad of impairments in autism spectrum disorders: a systematic review and meta-analysis

Autism is an extensively studied disorder in which the gender disparity in prevalence has received much attention. In contrast, only a few studies examine gender differences in symptomatology. This systematic review and meta-analysis of 22 peer reviewed original publications examines gender differences in the core triad of impairments in autism. Gender differences were transformed and concatenated using standardized mean differences, and analyses were stratified in five age categories (toddlerhood, preschool children, childhood, adolescence, young adulthood). Boys showed more repetitive and stereotyped behavior as from the age of six, but not below the age of six. Males and females did not differ in the domain of social behavior and communication. There is an underrepresentation of females with ASD an average to high intelligence. Females could present another autistic phenotype than males. As ASD is now defined according to the male phenotype this could imply that there is an ascertainment bias. More research is needed into the female phenotype of ASD with development of appropriate instruments to detect and ascertain them.

Gender-dependent effects of maternal immune activation on the behavior of mouse offspring

Autism spectrum disorders are neurodevelopmental disorders characterized by two core symptoms; impaired social interactions and communication, and ritualistic or repetitive behaviors. Both epidemiological and biochemical evidence suggests that a subpopulation of autistics may be linked to immune perturbations that occurred during fetal development. These findings have given rise to an animal model, called the "maternal immune activation" model, whereby the offspring from female rodents who were subjected to an immune stimulus during early or mid-pregnancy are studied. Here, C57BL/6 mouse dams were treated mid-gestation with saline, lipopolysaccharide (LPS) to mimic a bacterial infection, or polyinosinic:polycytidylic acid (Poly IC) to mimic a viral infection. Autism-associated behaviors were examined in the adult offspring of the treated dams. Behavioral tests were conducted to assess motor activity, exploration in a novel environment, sociability, and repetitive behaviors, and data analyses were carried independently on male and female mice. We observed a main treatment effect whereby male offspring from Poly IC-treated dams showed reduced motor activity. In the marble burying test of repetitive behavior, male offspring but not female offspring from both LPS and Poly IC-treated mothers showed increased marble burying. Our findings indicate that offspring from mothers subjected to immune stimulation during gestation show a gender-specific increase in stereotyped repetitive behavior.

Disentangling the heterogeneity of autism spectrum disorder through genetic findings

Autism spectrum disorder (ASD) represents a heterogeneous group of disorders, which presents a substantial challenge to diagnosis and treatment. Over the past decade, considerable progress has been made in the identification of genetic risk factors for ASD that define specific mechanisms and pathways underlying the associated behavioural deficits. In this Review, we discuss how some of the latest advances in the genetics of ASD have facilitated parsing of the phenotypic heterogeneity of this disorder. We argue that only through such advances will we begin to define endophenotypes that can benefit from targeted, hypothesis-driven treatments. We review the latest technologies used to identify and characterize the genetics underlying ASD and then consider three themes-single-gene disorders, the gender bias in ASD, and the genetics of neurological comorbidities-that highlight ways in which we can use genetics to define the many phenotypes within the autism spectrum. We also present current clinical guidelines for genetic testing in ASD and their implications for prognosis and treatment.

Repetitive behavior and restricted interests in young children with autism: comparisons with controls and stability over 2 years

Restricted, repetitive and stereotyped patterns of behavior, interests and activities [RRBs] are among the core symptoms of autism spectrum disorders (ASD). Previous studies have indicated that RRBs differentiate ASD from other developmental disorders and from typical development. This study examined the presentation of RRBs as reported on the Repetitive Behavior Scale-Revised, a caregiver report, in children with ASD [separated into autism and Pervasive Developmental Disorder-Not Otherwise Specified groups] compared with children with nonspectrum developmental delays or typical development. We examined the role of age, cognitive functioning, sex and social communication impairment as they relate to RRBs. The stability of RRBs in children with autism was also examined over the course of 2 years. Results of the study confirmed that the amount and type of RRBs differs by diagnosis. Age, cognitive functioning, sex and social-communication impairment were not significant correlates. Among children with autism, RRBs remained stable over time.