Developmental course of autistic social impairment in males. Dev Psychopathol. 2009;21:127-138. [PMID: 19144226 DOI: 10.1017/s095457940900008x]

Resting-state functional connectivity predicts longitudinal change in autistic traits and adaptive functioning in autism

Although typically identified in early childhood, the social communication symptoms and adaptive behavior deficits that are characteristic of autism spectrum disorder (ASD) persist throughout the lifespan. Despite this persistence, even individuals without cooccurring intellectual disability show substantial heterogeneity in outcomes. Previous studies have found various behavioral assessments [such as intelligence quotient (IQ), early language ability, and baseline autistic traits and adaptive behavior scores] to be predictive of outcome, but most of the variance in functioning remains unexplained by such factors. In this study, we investigated to what extent functional brain connectivity measures obtained from resting-state functional connectivity MRI (rs-fcMRI) could predict the variance left unexplained by age and behavior (follow-up latency and baseline autistic traits and adaptive behavior scores) in two measures of outcome--adaptive behaviors and autistic traits at least 1 y postscan (mean follow-up latency = 2 y, 10 mo). We found that connectivity involving the so-called salience network (SN), default-mode network (DMN), and frontoparietal task control network (FPTCN) was highly predictive of future autistic traits and the change in autistic traits and adaptive behavior over the same time period. Furthermore, functional connectivity involving the SN, which is predominantly composed of the anterior insula and the dorsal anterior cingulate, predicted reliable improvement in adaptive behaviors with 100% sensitivity and 70.59% precision. From rs-fcMRI data, our study successfully predicted heterogeneity in outcomes for individuals with ASD that was unaccounted for by simple behavioral metrics and provides unique evidence for networks underlying long-term symptom abatement.

Study protocol: a randomized controlled trial investigating the effects of a psychosexual training program for adolescents with autism spectrum disorder

BACKGROUND

Previous research shows that adolescents with autism spectrum disorder (ASD) run several risks in their psychosexual development and that these adolescents can have limited access to reliable information on puberty and sexuality, emphasizing the need for specific guidance of adolescents with ASD in their psychosexual development. Few studies have investigated the effects of psychosexual training programs for adolescents with ASD and to date no randomized controlled trials are available to study the effects of psychosexual interventions for this target group.

METHODS/DESIGN

The randomized controlled trial (RCT) described in this study protocol aims to investigate the effects of the Tackling Teenage Training (TTT) program on the psychosexual development of adolescents with ASD. This parallel clinical trial, conducted in the South-West of the Netherlands, has a simple equal randomization design with an intervention and a waiting-list control condition. Two hundred adolescents and their parents participate in this study. We assess the participants in both conditions using self-report as well as parent-report questionnaires at three time points during 1 year: at baseline (T1), post-treatment (T2), and for follow-up (T3).

DISCUSSION

To our knowledge, the current study is the first that uses a randomized controlled design to study the effects of a psychosexual training program for adolescents with ASD. It has a number of methodological strengths, namely a large sample size, a wide range of functionally relevant outcome measures, the use of multiple informants, and a standardized research and intervention protocol. Also some limitations of the described study are identified, for instance not making a comparison between two treatment conditions, and no use of blinded observational measures to investigate the ecological validity of the research results.

TRIAL REGISTRATION

Dutch Trial Register NTR2860. Registered on 20 April 2011.

Association of autistic traits in adulthood with childhood abuse, interpersonal victimization, and posttraumatic stress

Persons with autistic traits may be at elevated risk for interpersonal victimization across the life course. Children with high levels of autistic traits may be targeted for abuse, and deficits in social awareness may increase risk of interpersonal victimization. Additionally, persons with autistic traits may be at elevated risk of posttraumatic stress disorder (PTSD) symptoms subsequent to trauma. We examined retrospectively reported prevalence of childhood abuse, trauma victimization and PTSD symptoms by autistic traits among adult women in a population-based longitudinal cohort, the Nurses' Health Study II (N=1,077). Autistic traits were measured by the 65-item Social Responsiveness Scale. We estimated odds ratios (OR) for childhood sexual and physical/emotional abuse and PTSD symptoms by quintiles of autistic traits. We examined possible mediation of PTSD risk by abuse and trauma type. Women in the highest versus lowest quintile of autistic traits were more likely to have been sexually abused (40.1% versus 26.7%), physically/emotionally abused (23.9% versus 14.3%), mugged (17.1% versus 10.1%), pressured into sexual contact (25.4% versus 15.6%) and have high PTSD symptoms (10.7% versus 4.5%). Odds of PTSD were elevated in women in the top three quintiles of autistic traits compared with the reference group (OR range=1.4 to 1.9). Childhood abuse exposure partly accounted for elevated risk of PTSD in women with autistic traits. We identify for the first time an association between autistic traits, childhood abuse, trauma victimization, and PTSD. Levels of autistic traits that are highly prevalent in the general population are associated with abuse, trauma and PTSD.

Systematic review of tools to measure outcomes for young children with autism spectrum disorder

BACKGROUND

The needs of children with autism spectrum disorder (ASD) are complex and this is reflected in the number and diversity of outcomes assessed and measurement tools used to collect evidence about children's progress. Relevant outcomes include improvement in core ASD impairments, such as communication, social awareness, sensory sensitivities and repetitiveness; skills such as social functioning and play; participation outcomes such as social inclusion; and parent and family impact.

OBJECTIVES

To examine the measurement properties of tools used to measure progress and outcomes in children with ASD up to the age of 6 years. To identify outcome areas regarded as important by people with ASD and parents.

METHODS

The MeASURe (Measurement in Autism Spectrum disorder Under Review) research collaboration included ASD experts and review methodologists. We undertook systematic review of tools used in ASD early intervention and observational studies from 1992 to 2013; systematic review, using the COSMIN checklist (Consensus-based Standards for the selection of health Measurement Instruments) of papers addressing the measurement properties of identified tools in children with ASD; and synthesis of evidence and gaps. The review design and process was informed throughout by consultation with stakeholders including parents, young people with ASD, clinicians and researchers.

RESULTS

The conceptual framework developed for the review was drawn from the International Classification of Functioning, Disability and Health, including the domains 'Impairments', 'Activity Level Indicators', 'Participation', and 'Family Measures'. In review 1, 10,154 papers were sifted - 3091 by full text - and data extracted from 184; in total, 131 tools were identified, excluding observational coding, study-specific measures and those not in English. In review 2, 2665 papers were sifted and data concerning measurement properties of 57 (43%) tools were extracted from 128 papers. Evidence for the measurement properties of the reviewed tools was combined with information about their accessibility and presentation. Twelve tools were identified as having the strongest supporting evidence, the majority measuring autism characteristics and problem behaviour. The patchy evidence and limited scope of outcomes measured mean these tools do not constitute a 'recommended battery' for use. In particular, there is little evidence that the identified tools would be good at detecting change in intervention studies. The obvious gaps in available outcome measurement include well-being and participation outcomes for children, and family quality-of-life outcomes, domains particularly valued by our informants (young people with ASD and parents).

CONCLUSIONS

This is the first systematic review of the quality and appropriateness of tools designed to monitor progress and outcomes of young children with ASD. Although it was not possible to recommend fully robust tools at this stage, the review consolidates what is known about the field and will act as a benchmark for future developments. With input from parents and other stakeholders, recommendations are made about priority targets for research.

FUTURE WORK

Priorities include development of a tool to measure child quality of life in ASD, and validation of a potential primary outcome tool for trials of early social communication intervention.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42012002223.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Lack of effect of risperidone on core autistic symptoms: data from a longitudinal study

OBJECTIVE

The purpose of this study was to investigate the course of autistic symptoms, using a quantitative measure of core autistic traits, among risperidone-treated children who participated in a 10 year life course longitudinal study.

METHODS

Parents completed surveys of intervention history, as well as serial symptom severity measurements using the Social Responsiveness Scale (SRS), on their autism spectrum disorder (ASD)-affected children. Fifty participants (out of a total of 184 with full intervention histories) were reported to have been treated with risperidone during the course of the study. Serial SRS scores during risperidone treatment were available for a majority of children whose parents reported a positive effect from risperidone.

RESULTS

Two thirds of risperidone-treated children (n=33) were reported by parents to have improved by taking the medication, with the principal effects described being that children were calmer, better focused, and less aggressive. SRS scores of children reported to have responded positively to risperidone did not improve over time.

CONCLUSIONS

Risperidone's beneficial effect on aggression and other elements of adaptive functioning were not necessarily accompanied by reduction in core ASD symptoms, as serially assessed by the same caregivers who reported improvement in their children. These results reflect the distinction between reduction in core symptom burden and improvement in adaptive functioning. Given the cumulative risks of atypical neuroleptics, the findings underscore the importance of periodic re-evaluation of medication benefit for children with ASD receiving neuroleptic treatment.

Sulforaphane treatment of autism spectrum disorder (ASD)

Autism spectrum disorder (ASD), characterized by both impaired communication and social interaction, and by stereotypic behavior, affects about 1 in 68, predominantly males. The medico-economic burdens of ASD are enormous, and no recognized treatment targets the core features of ASD. In a placebo-controlled, double-blind, randomized trial, young men (aged 13-27) with moderate to severe ASD received the phytochemical sulforaphane (n = 29)--derived from broccoli sprout extracts--or indistinguishable placebo (n = 15). The effects on behavior of daily oral doses of sulforaphane (50-150 µmol) for 18 wk, followed by 4 wk without treatment, were quantified by three widely accepted behavioral measures completed by parents/caregivers and physicians: the Aberrant Behavior Checklist (ABC), Social Responsiveness Scale (SRS), and Clinical Global Impression Improvement Scale (CGI-I). Initial scores for ABC and SRS were closely matched for participants assigned to placebo and sulforaphane. After 18 wk, participants receiving placebo experienced minimal change (<3.3%), whereas those receiving sulforaphane showed substantial declines (improvement of behavior): 34% for ABC (P < 0.001, comparing treatments) and 17% for SRS scores (P = 0.017). On CGI-I, a significantly greater number of participants receiving sulforaphane had improvement in social interaction, abnormal behavior, and verbal communication (P = 0.015-0.007). Upon discontinuation of sulforaphane, total scores on all scales rose toward pretreatment levels. Dietary sulforaphane, of recognized low toxicity, was selected for its capacity to reverse abnormalities that have been associated with ASD, including oxidative stress and lower antioxidant capacity, depressed glutathione synthesis, reduced mitochondrial function and oxidative phosphorylation, increased lipid peroxidation, and neuroinflammmation.

Parental social responsiveness and risk of autism spectrum disorder in offspring

IMPORTANCE

Although autism spectrum disorder (ASD) is known to be heritable, patterns of inheritance of subclinical autistic traits in nonclinical samples are poorly understood.

OBJECTIVE

To examine the familiality of Social Responsiveness Scale (SRS) scores of individuals with and without ASD.

DESIGN, SETTING, AND PARTICIPANTS

We performed a nested case-control study (pilot study: July 1, 2007, through June 30, 2009; full-scale study: September 15, 2008, through September 14, 2012) within a population-based longitudinal cohort. Participants were drawn from the Nurses' Health Study II, a cohort of 116,430 female nurses recruited in 1989. Case participants were index children with reported ASD; control participants were frequency matched by year of birth of case participants among those not reporting ASD. Of 3161 eligible participants, 2144 nurses (67.8%) returned SRS forms for a child and at least 1 parent and were included in these analyses.

EXPOSURE

The SRS scores, as reported by nurse mothers and their spouses, were examined in association with risk of ASD using crude and adjusted logistic regression analyses. The SRS scores of the children were examined in association with SRS scores of the parents using crude and adjusted linear regression analyses stratified by case status.

MAIN OUTCOMES AND MEASURES

Autism spectrum disorder, assessed by maternal report, validated in a subgroup with the Autism Diagnostic Interview-Revised.

RESULTS

A total of 1649 individuals were included in these analyses, including 256 ASD case participants, 1393 control participants, 1233 mothers, and 1614 fathers. Risk of ASD was increased by 85.0% among children whose parents had concordantly elevated SRS scores (odds ratio [OR], 1.85; 95% CI, 1.08-3.16) and by 52.0% when the score of either parent was elevated (OR, 1.52; 95% CI, 1.11-2.06). Elevated scores of the father significantly increased the risk of ASD in the child (OR, 1.94; 95% CI, 1.38-2.71), but no association was seen with elevated scores of the mother. Elevated parent scores significantly increased child scores in controls, corresponding to an increase in 23 points (P < .001).

CONCLUSIONS AND RELEVANCE

These findings support the role of additive genetic influences in concentrating inherited ASD susceptibility in successive generations and the potential role of preferential mating, and suggest that typical variation in parental social functioning can produce clinically significant differences in offspring social traits.

Reciprocal social behavior in youths with psychotic illness and those at clinical high risk

Youths at clinical high risk (CHR) for psychosis typically exhibit significant social dysfunction. However, the specific social behaviors associated with psychosis risk have not been well characterized. We administer the Social Responsiveness Scale (SRS), a measure of autistic traits that examines reciprocal social behavior, to the parents of 117 adolescents (61 CHR individuals, 20 age-matched adolescents with a psychotic disorder [AOP], and 36 healthy controls) participating in a longitudinal study of psychosis risk. AOP and CHR individuals have significantly elevated SRS scores relative to healthy controls, indicating more severe social deficits. Mean scores for AOP and CHR youths are typical of scores obtained in individuals with high functioning autism (Constantino & Gruber, 2005). SRS scores are significantly associated with concurrent real-world social functioning in both clinical groups. Finally, baseline SRS scores significantly predict social functioning at follow-up (an average of 7.2 months later) in CHR individuals, over and above baseline social functioning measures (p < .009). These findings provide novel information regarding impairments in domains critical for adolescent social development, because CHR individuals and those with overt psychosis show marked deficits in reciprocal social behavior. Further, the SRS predicts subsequent real-world social functioning in CHR youth, suggesting that this measure may be useful for identifying targets of treatment in psychosocial interventions.

Strong genetic influences on the stability of autistic traits in childhood

OBJECTIVE

Disorders on the autism spectrum, as well as autistic traits in the general population, have been found to be both highly stable across age and highly heritable at individual ages. However, little is known about the overlap in genetic and environmental influences on autistic traits across age and the contribution of such influences to trait stability itself. The present study investigated these questions in a general population sample of twins.

METHOD

More than 6,000 twin pairs were rated on an established scale of autistic traits by their parents at 8, 9, and 12 years of age and by their teachers at 9 and 12 years of age. Data were analyzed using structural equation modeling.

RESULTS

The results indicated that, consistently across raters, not only were autistic traits stable, and moderately to highly heritable at individual ages, but there was also a high degree of overlap in genetic influences across age. Furthermore, autistic trait stability could largely be accounted for by genetic factors, with the environment unique to each twin playing a minor role. The environment shared by twins had virtually no effect on the longitudinal stability in autistic traits.

CONCLUSIONS

Autistic traits are highly stable across middle childhood. and this stability is caused primarily by genetic factors.

Common variation contributes to the genetic architecture of social communication traits

BACKGROUND

Social communication difficulties represent an autistic trait that is highly heritable and persistent during the course of development. However, little is known about the underlying genetic architecture of this phenotype.

METHODS

We performed a genome-wide association study on parent-reported social communication problems using items of the children's communication checklist (age 10 to 11 years) studying single and/or joint marker effects. Analyses were conducted in a large UK population-based birth cohort (Avon Longitudinal Study of Parents and their Children, ALSPAC, N = 5,584) and followed-up within a sample of children with comparable measures from Western Australia (RAINE, N = 1364).

RESULTS

Two of our seven independent top signals (P-discovery <1.0E-05) were replicated (0.009

CONCLUSION

Overall, our study provides both joint and single-SNP-based evidence for the contribution of common polymorphisms to variation in social communication phenotypes.

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Key Words

• alspac
• raine
• autistic trait
• gwas
• social communication
• association

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MESH Headings Collapse

Grants

• MC_UU_12013/1 Medical Research Council
• G0800582 Medical Research Council
• MC_PC_15018 Medical Research Council
• G9815508 Medical Research Council
• MC_UU_12013/4 Medical Research Council
• MC_UU_12013/3 Medical Research Council
• U01 HG006830 NHGRI NIH HHS

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Affiliation(s)

Beate St Pourcain MRC Integrative Epidemiology Unit, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK School of Oral and Dental Sciences, University of Bristol, Bristol, UK School of Experimental Psychology, University of Bristol, Bristol, UK
Andrew J O Whitehouse Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Australia School of Psychology, University of Western Australia, Perth, Australia
Wei Q Ang School of Women’s and Infants’ Health, University of Western Australia, Perth, Australia
Nicole M Warrington School of Women’s and Infants’ Health, University of Western Australia, Perth, Australia
Joseph T Glessner Children’s Hospital of Philadelphia, Philadelphia, PA, USA
Kai Wang Zilkha Neurogenetic Institute & Department of Psychiatry, University of Southern California, Los Angeles, CA, USA
Nicholas J Timpson MRC Integrative Epidemiology Unit, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK
David M Evans MRC Integrative Epidemiology Unit, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK
John P Kemp MRC Integrative Epidemiology Unit, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK
Susan M Ring School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK
Wendy L McArdle School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK
Jean Golding School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK
Hakon Hakonarson Children’s Hospital of Philadelphia, Philadelphia, PA, USA
Craig E Pennell School of Women’s and Infants’ Health, University of Western Australia, Perth, Australia
George Davey Smith MRC Integrative Epidemiology Unit, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK School of Social and Community Medicine, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, UK

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Confirmatory factor analytic structure and measurement invariance of quantitative autistic traits measured by the social responsiveness scale-2

Understanding the factor structure of autistic symptomatology is critical to the discovery and interpretation of causal mechanisms in autism spectrum disorder. We applied confirmatory factor analysis and assessment of measurement invariance to a large (N = 9635) accumulated collection of reports on quantitative autistic traits using the Social Responsiveness Scale, representing a broad diversity of age, severity, and reporter type. A two-factor structure (corresponding to social communication impairment and restricted, repetitive behavior) as elaborated in the updated Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) criteria for autism spectrum disorder exhibited acceptable model fit in confirmatory factor analysis. Measurement invariance was appreciable across age, sex, and reporter (self vs other), but somewhat less apparent between clinical and nonclinical populations in this sample comprised of both familial and sporadic autism spectrum disorders. The statistical power afforded by this large sample allowed relative differentiation of three factors among items encompassing social communication impairment (emotion recognition, social avoidance, and interpersonal relatedness) and two factors among items encompassing restricted, repetitive behavior (insistence on sameness and repetitive mannerisms). Cross-trait correlations remained extremely high, that is, on the order of 0.66-0.92. These data clarify domains of statistically significant factoral separation that may relate to partially-but not completely-overlapping biological mechanisms, contributing to variation in human social competency. Given such robust intercorrelations among symptom domains, understanding their co-emergence remains a high priority in conceptualizing common neural mechanisms underlying autistic syndromes.

Potential for treatment of severe autism in tuberous sclerosis complex

The Food and Drug Administration (FDA) has approved two mechanism-based treatments for tuberous sclerosis complex (TSC)-everolimus and vigabatrin. However, these treatments have not been systematically studied in individuals with TSC and severe autism. The aim of this review is to identify the clinical features of severe autism in TSC, applicable preclinical models, and potential barriers that may warrant strategic planning in the design phase of clinical trial development. A comprehensive search strategy was formed and searched across PubMed, Embase and SCOPUS from their inception to 2/21/12, 3/16/12, and 3/12/12 respectively. After the final search date, relevant, updated articles were selected from PubMed abstracts generated electronically and emailed daily from PubMed. The references of selected articles were searched, and relevant articles were selected. A search of clinicaltrials.gov was completed using the search term “TSC” and “tuberous sclerosis complex”. Autism has been reported in as many as 60% of individuals with TSC; however, review of the literature revealed few data to support clear classification of the severity of autism in TSC. Variability was identified in the diagnostic approach, assessment of cognition, and functional outcome among the reviewed studies and case reports. Objective outcome measures were not used in many early studies; however, diffusion tensor imaging of white matter, neurophysiologic variability in infantile spasms, and cortical tuber subcategories were examined in recent studies and may be useful for objective classification of TSC in future studies. Mechanism-based treatments for TSC are currently available. However, this literature review revealed two potential barriers to successful design and implementation of clinical trials in individuals with severe autism-an unclear definition of the population and lack of validated outcome measures. Recent studies of objective outcome measures in TSC and further study of applicable preclinical models present an opportunity to overcome these barriers.

Progress toward treatments for synaptic defects in autism

Autism spectrum disorder (ASD) encompasses a range of disorders that are characterized by social and communication deficits and repetitive behaviors. For the majority of affected individuals, the cause of ASD remains unknown, but in at least 20% of the cases, a genetic cause can be identified. There is currently no cure for ASD; however, results from mouse models indicate that some forms of the disorder could be alleviated even at the adult stage. Genes involved in ASD seem to converge on common pathways altering synaptic homeostasis. We propose, given the clinical heterogeneity of ASD, that specific 'synaptic clinical trials' should be designed and launched with the aim of establishing whether phenotype 'reversals' could also occur in humans.

A comparison of three self-report measures of the broader autism phenotype in a non-clinical sample

Three self-report measures of the broader autism phenotype (BAP) were evaluated in terms of their internal consistency, distribution of scores, factor structure, and criterion-related validity in a non-clinical sample. All measures showed a continuous distribution. The SRS-A and BAPQ showed expected sex differences and were superior to the AQ in terms of internal consistency. The proposed factor structure of the BAPQ replicated better than the proposed structures of the other measures. All measures showed evidence of criterion validity via correlations with related constructs and each measure incremented the others in predicting related constructs. However, the SRS-A and BAPQ were generally stronger in this domain. Recommendations for the use of these instruments for measuring the BAP in non-clinical populations are discussed.

Measuring change in social interaction skills of young children with autism

Designing effective treatments for improving early social behaviors in autism has been identified as a critical research need. One barrier to drawing conclusions about optimal treatments for children with autism is the use of highly varied dependent measures in the treatment literature. Contributing to this is the absence of "gold standard" assessment batteries. This is particularly true for assessing changes in social interaction impairments in very young children with autism. This paper addresses this issue by reviewing variables important in the development and evaluation of assessment measures, discussing previous studies' choices of socially-related dependent measures, and the strengths, limitations, and research questions pertaining to them. It concludes with recommendations for measurement selection and future directions for research.

Distinct cortical correlates of autistic versus antisocial traits in a longitudinal sample of typically developing youth

In humans, behaviors associated with autism and antisociality, disorders characterized by distinct social impairments, can be viewed as quantitative traits that range from frank impairment to normal variation, as found in the general population. Neuroimaging investigations of autism and antisociality demonstrate diagnostically specific aberrant cortical brain structure. However, little is known about structural brain correlates of social behavior in nonclinical populations. Therefore, we sought to determine whether autistic and antisocial traits exhibit dissociable cortical correlates and whether these associations are stable across development among typically developing youth. Three hundred twenty-three typically developing youth (age at first scan: mean = 10.63, SD = 3.71 years) underwent anatomic magnetic resonance imaging (1-6 scans each; total = 742 scans), and provided ratings of autistic and antisocial traits. Higher autistic trait ratings were associated with thinner cortex most prominently in right superior temporal sulcus while higher antisocial trait ratings were associated with thinner cortex in primarily bilateral anterior prefrontal cortices. There was no interaction with age, indicating that these brain-behavior associations were stable across development. Using assessments of both subclinical autistic and subclinical antisocial traits within a large longitudinal sample of typically developing youth, we demonstrate dissociable neuroanatomic correlations that parallel those found in the frank clinical disorders of autism (e.g., superior temporal cortex) and antisociality (e.g., anterior prefrontal cortex). Moreover, these correlations appear to be established in early childhood and remain fixed into early adulthood. These results support the dimensional view of psychopathology and provide neural signatures that can serve as informative endophenotypes for future genetic studies.

Links between co-occurring social-communication and hyperactive-inattentive trait trajectories

OBJECTIVE

There is overlap between an autistic and hyperactive-inattentive symptomatology when studied cross-sectionally. This study is the first to examine the longitudinal pattern of association between social-communication deficits and hyperactive-inattentive symptoms in the general population, from childhood through adolescence. We explored the interrelationship between trajectories of co-occurring symptoms, and sought evidence for shared prenatal/perinatal risk factors.

METHOD

Study participants were 5,383 singletons of white ethnicity from the Avon Longitudinal Study of Parents and Children (ALSPAC). Multiple measurements of hyperactive-inattentive traits (Strengths and Difficulties Questionnaire) and autistic social-communication impairment (Social Communication Disorder Checklist) were obtained between 4 and 17 years. Both traits and their trajectories were modeled in parallel using latent class growth analysis (LCGA). Trajectory membership was subsequently investigated with respect to prenatal/perinatal risk factors.

RESULTS

LCGA analysis revealed two distinct social-communication trajectories (persistently impaired versus low-risk) and four hyperactive-inattentive trait trajectories (persistently impaired, intermediate, childhood-limited and low-risk). Autistic symptoms were more stable than those of attention-deficit/hyperactivity disorder (ADHD) behaviors, which showed greater variability. Trajectories for both traits were strongly but not reciprocally interlinked, such that the majority of children with a persistent hyperactive-inattentive symptomatology also showed persistent social-communication deficits but not vice versa. Shared predictors, especially for trajectories of persistent impairment, were maternal smoking during the first trimester, which included familial effects, and a teenage pregnancy.

CONCLUSIONS

Our longitudinal study reveals that a complex relationship exists between social-communication and hyperactive-inattentive traits. Patterns of association change over time, with corresponding implications for removing exclusivity criteria for ASD and ADHD, as proposed for DSM-5.

Are autistic traits in the general population stable across development?

There is accumulating evidence that autistic traits (AT) are on a continuum in the general population, with clinical autism representing the extreme end of a quantitative distribution. While the nature and severity of symptoms in clinical autism are known to persist over time, no study has examined the long-term stability of AT among typically developing toddlers. The current investigation measured AT in 360 males and 400 males from the general population close to two decades apart, using the Pervasive Developmental Disorder subscale of the Child Behavior Checklist in early childhood (M = 2.14 years; SD = 0.15), and the Autism-Spectrum Quotient in early adulthood (M = 19.50 years; SD = 0.70). Items from each scale were further divided into social (difficulties with social interaction and communication) and non-social (restricted and repetitive behaviours and interests) AT. The association between child and adult measurements of AT as well the influence of potentially confounding sociodemographic, antenatal and obstetric variables were assessed using Pearson's correlations and linear regression. For males, Total AT in early childhood were positively correlated with total AT (r = .16, p = .002) and social AT (r = .16, p = .002) in adulthood. There was also a positive correlation for males between social AT measured in early childhood and Total (r = .17, p = .001) and social AT (r = .16, p = .002) measured in adulthood. Correlations for non-social AT did not achieve significance in males. Furthermore, there was no significant longitudinal association in AT observed for males or females. Despite the constraints of using different measures and different raters at the two ages, this study found modest developmental stability of social AT from early childhood to adulthood in boys.

Association of oxytocin receptor (OXTR) gene variants with multiple phenotype domains of autism spectrum disorder

Autism spectrum disorder (ASD) is characterized by core deficits in social behavior, communication, and behavioral flexibility. Several lines of evidence indicate that oxytocin, signaling through its receptor (OXTR), is important in a wide range of social behaviors. In attempts to determine whether genetic variations in the oxytocin signaling system contribute to ASD susceptibility, seven recent reports indicated association of common genetic polymorphisms in the OXTR gene with ASD. Each involved relatively small sample sizes (57 to 436 families) and, where it was examined, failed to identify association of OXTR polymorphisms with measures of social behavior in individuals with ASD. We report genetic association analysis of 25 markers spanning the OXTR locus in 1,238 pedigrees including 2,333 individuals with ASD. Association of three markers previously implicated in ASD susceptibility, rs2268493 (P = 0.043), rs1042778 (P = 0.037), and rs7632287 (P = 0.016), was observed. Further, these genetic markers were associated with multiple core ASD phenotypes, including social domain dysfunction, measured by standardized instruments used to diagnose and describe ASD. The data suggest association of OXTR genetic polymorphisms with ASD, although the results should be interpreted with caution because none of the significant associations would survive appropriate correction for multiple comparisons. However, the current findings of association in a large independent cohort are consistent with previous results, and the biological plausibility of participation of the oxytocin signaling system in modulating social disruptions characteristic of ASD, suggest that functional polymorphisms of OXTR may contribute to ASD risk in a subset of families.

The quantitative nature of autistic social impairment

Autism, like intellectual disability, represents the severe end of a continuous distribution of developmental impairments that occur in nature, that are highly inherited, and that are orthogonally related to other parameters of development. A paradigm shift in understanding the core social abnormality of autism as a quantitative trait rather than as a categorically defined condition has key implications for diagnostic classification, the measurement of change over time, the search for underlying genetic and neurobiologic mechanisms, and public health efforts to identify and support affected children. Here, a recent body of research in genetics and epidemiology is presented to examine a dimensional reconceptualization of autistic social impairment-as manifested in clinical autistic syndromes, the broader autism phenotype, and normal variation in the general population. It illustrates how traditional categorical approaches to diagnosis may lead to misclassification of subjects (especially girls and mildly affected boys in multiple-incidence autism families), which can be particularly damaging to biological studies and proposes continued efforts to derive a standardized quantitative system by which to characterize this family of conditions.

Stability of autistic traits in the general population: further evidence for a continuum of impairment

OBJECTIVE

This study investigated the developmental course of autistic traits in a nationally representative sample of subjects 7 to 13 years of age.

METHOD

The parents of 6,539 children in the Avon Longitudinal Study of Parents and Children completed the Social and Communication Disorders Checklist at ages 7, 10, and 13. The phenotypic progression of autistic traits was assessed in the full sample and in high-scoring individuals (e.g., top 10%, 5%). Gender, IQ, and overall behavior difficulties were examined as potentially relevant influences on autistic trait trajectories.

RESULTS

Autistic traits were highly stable in the general population overall and in the high-scoring groups. In the full sample, there was no change in mean Social and Communication Disorders Checklist scores for female subjects ages 7 to 13 (p = .43). Scores for male subjects decreased slightly, but significantly, on the order of 0.1 standard deviations (p < .001). There was no mean change in parent-rated autistic traits within any of the high-scoring groups. IQ was not related to phenotypic progression; high parent-rated behavior problems predicted slight improvement in Social and Communication Disorders Checklist scores over the course of the study period in high-scoring individuals (p < .01).

CONCLUSIONS

These findings suggest that autistic traits are highly stable in the general population, even in individuals with the highest concentrations of autism-like behaviors. Phenotypic stability is consistent with expectations for individuals with autism spectrum disorders, providing further support for a phenomenologic continuum across the clinical threshold. Moreover, the gap between female and male risk for autistic symptomology is consistent over time.

Autism spectrum disorders and autistic traits: a decade of new twin studies

Researchers continue to pursue a better understanding of the symptoms, comorbidities, and causes of autism spectrum disorders. In this article we review more than 30 twin studies of autism spectrum disorders (ASDs) and autistic traits published in the last decade that have contributed to this endeavor. These twin studies have reported on the heritability of autism spectrum disorders and autistic traits in different populations and using different measurement and age groups. These studies have also stimulated debate and new hypotheses regarding why ASDs show substantial symptom heterogeneity, and what causes their comorbidity with intellectual disability, language delay, and other psychiatric disorders such as ADHD. These studies also reveal that the etiology of autism and autistic traits assessed in the general population is more similar than different, which contributes to the question of where the boundary lies between autism and typical development. Recent findings regarding molecular genetic and environmental causes of autism are discussed in the relation to these twin studies. Lastly, methodological assumptions of the twin design are given consideration, as well as issues of measurement. Future research directions are suggested to ensure that this decade is as productive as the last in attempting to disentangle the causes of autism spectrum disorders.

Sibling recurrence and the genetic epidemiology of autism

OBJECTIVE

Although the symptoms of autism exhibit quantitative distributions in nature, estimates of recurrence risk in families have never previously considered or incorporated quantitative characterization of the autistic phenotype among siblings.

METHOD

The authors report the results of quantitative characterization of 2,920 children from 1,235 families participating in a national volunteer register, with at least one child clinically affected by an autism spectrum disorder and at least one full biological sibling.

RESULTS

A traditionally defined autism spectrum disorder in an additional child occurred in 10.9% of the families. An additional 20% of nonautism-affected siblings had a history of language delay, one-half of whom exhibited autistic qualities of speech. Quantitative characterization using the Social Responsiveness Scale supported previously reported aggregation of a wide range of subclinical (quantitative) autistic traits among otherwise unaffected children in multiple-incidence families and a relative absence of quantitative autistic traits among siblings in single-incidence families. Girls whose standardized severity ratings fell above a first percentile severity threshold (relative to the general population distribution) were significantly less likely to have elicited community diagnoses than their male counterparts.

CONCLUSIONS

These data suggest that, depending on how it is defined, sibling recurrence in autism spectrum disorder may exceed previously published estimates and varies as a function of family type. The results support differences in mechanisms of genetic transmission between simplex and multiplex autism and advance current understanding of the genetic epidemiology of autism spectrum conditions.

Can family affectedness inform infant sibling outcomes of autism spectrum disorders?

BACKGROUND

Difficulties in communication and reciprocal social behavior are core features of autism spectrum disorders (ASD) and are often present, to varying degrees, in other family members. This prospective longitudinal infant sibling study examines whether social-communicative features of family members may inform which infants are at increased risk for ASD and other developmental concerns.

METHOD

Two hundred and seventeen families participated in this study. Infant siblings were recruited from families with at least one older child diagnosed with an ASD (n = 135) or at least one typically developing older child (n = 82). Families completed the Social Responsiveness Scale to assess social and communication features of the broader autism phenotype (BAP), sometimes called quantitative autistic traits (QAT). Family affectedness was assessed in two ways: categorically, based on number of affected older siblings (i.e., typical, simplex, multiplex risk groups) and dimensionally, by assessing varying degrees of QAT in all family members. Infant siblings were assessed at 36 months of age and completed the Autism Diagnostic Observation Schedule and the Mullen Scales of Early Learning.

RESULTS

In structural equation models, comparisons between multiplex, simplex and typical groups revealed the highest rates of QAT in the multiplex group followed by the simplex and typical groups. Infant sibling outcomes were predicted by gender, family risk group, proband QAT, and additional sibling QAT.

CONCLUSIONS

Replicating previous cross-sectional and family history findings, the present study found elevated social and communication features of the BAP in siblings and fathers of ASD families, but not in mothers. While social and communication features of the BAP in mothers, fathers, and undiagnosed siblings did not predict infant sibling outcomes, having more than one affected older sibling did. Infant siblings from multiplex families were at significantly higher risk for ASD than infant siblings from simplex families in this sample.

Genome-wide linkage using the Social Responsiveness Scale in Utah autism pedigrees

BACKGROUND

Autism Spectrum Disorders (ASD) are phenotypically heterogeneous, characterized by impairments in the development of communication and social behaviour and the presence of repetitive behaviour and restricted interests. Dissecting the genetic complexity of ASD may require phenotypic data reflecting more detail than is offered by a categorical clinical diagnosis. Such data are available from the Social Responsiveness Scale (SRS) which is a continuous, quantitative measure of social ability giving scores that range from significant impairment to above average ability.

METHODS

We present genome-wide results for 64 multiplex and extended families ranging from two to nine generations. SRS scores were available from 518 genotyped pedigree subjects, including affected and unaffected relatives. Genotypes from the Illumina 6 k single nucleotide polymorphism panel were provided by the Center for Inherited Disease Research. Quantitative and qualitative analyses were done using MCLINK, a software package that uses Markov chain Monte Carlo (MCMC) methods to perform multilocus linkage analysis on large extended pedigrees.

RESULTS

When analysed as a qualitative trait, linkage occurred in the same locations as in our previous affected-only genome scan of these families, with findings on chromosomes 7q31.1-q32.3 [heterogeneity logarithm of the odds (HLOD) = 2.91], 15q13.3 (HLOD = 3.64), and 13q12.3 (HLOD = 2.23). Additional positive qualitative results were seen on chromosomes 6 and 10 in regions that may be of interest for other neuropsychiatric disorders. When analysed as a quantitative trait, results replicated a peak found in an independent sample using quantitative SRS scores on chromosome 11p15.1-p15.4 (HLOD = 2.77). Additional positive quantitative results were seen on chromosomes 7, 9, and 19.

CONCLUSIONS

The SRS linkage peaks reported here substantially overlap with peaks found in our previous affected-only genome scan of clinical diagnosis. In addition, we replicated a previous SRS peak in an independent sample. These results suggest the SRS is a robust and useful phenotype measure for genetic linkage studies of ASD. Finally, analyses of SRS scores revealed linkage peaks overlapping with evidence from other studies of neuropsychiatric diseases. The information available from the SRS itself may, therefore, reveal locations for autism susceptibility genes that would not otherwise be detected.

Familial aggregation of quantitative autistic traits in multiplex versus simplex autism

Recent research has suggested that the mode of inheritance for simplex autism (SA, one individual in the family affected) may be distinct from that for multiplex autism (MA, two or more individuals affected). Since sub clinical autistic traits have been observed in "unaffected" relatives of children with autism, we explored whether the distributions of such traits in families supported differential modes of genetic transmission for SA and MA autism. We measured patterns of familial aggregation of quantitative autistic traits (QAT) in children and parents in 80 SA families and 210 MA families, using the Social Responsiveness Scale. When considering all SA and MA siblings who scored below a uniform quantitative (clinical-level) severity threshold, MA brothers exhibited a distinct pathological shift in the distribution, compared to SA brothers (P < 0.0001). Such aggregation of QAT was also observed in fathers but not among females in MA families. Significant spousal correlations for QAT-suggestive of assortative mating-were observed in both SA and MA families, but neither group was characterized by a greater-than-chance level of concordant elevation among spousal pairs in this volunteer sample. Among male first degree relatives, there exist distinct patterns of QAT manifestation for simplex versus multiplex autism. These findings are consistent with the results of molecular genetic studies that have suggested differential modes of intergenerational transmission for SA and MA. Characterization of QAT and other endophenotypes among close relatives may be useful for reducing sample heterogeneity in future genetic and neurobiologic studies of autism.

Multi-informant ratings of psychiatric symptom severity in children with autism spectrum disorders: the importance of environmental context

The present study examines co-occurring psychiatric syndromes in a well-characterized sample of youths with autism spectrum disorders (ASD; n = 177) and their siblings (n = 148), reported independently by parents and teachers. In ASD, parents reported substantial comorbidity with affective (26%), anxiety (25%), attentional (25%), conduct (16%), oppositional (15%), and somatic problems (6%). Teachers reported a much lower prevalence. Autistic severity scores for children with ASD exhibited moderate correlations with general psychopathology within- but not across-informants, whereas, sibling correlations were significant both within- and across-informants. Results support the role of environmental context in psychiatric symptom expression in children affected by autism and suggest that informant discrepancies may more provide critical cues for these children via specific environmental modifications.