Can standard measures identify subclinical markers of autism?

Endophenotype trait domains for advancing gene discovery in autism spectrum disorder

Autism spectrum disorder (ASD) is associated with a diverse range of etiological processes, including both genetic and non-genetic causes. For a plurality of individuals with ASD, it is likely that the primary causes involve multiple common inherited variants that individually account for only small levels of variation in phenotypic outcomes. This genetic landscape creates a major challenge for detecting small but important pathogenic effects associated with ASD. To address similar challenges, separate fields of medicine have identified endophenotypes, or discrete, quantitative traits that reflect genetic likelihood for a particular clinical condition and leveraged the study of these traits to map polygenic mechanisms and advance more personalized therapeutic strategies for complex diseases. Endophenotypes represent a distinct class of biomarkers useful for understanding genetic contributions to psychiatric and developmental disorders because they are embedded within the causal chain between genotype and clinical phenotype, and they are more proximal to the action of the gene(s) than behavioral traits. Despite their demonstrated power for guiding new understanding of complex genetic structures of clinical conditions, few endophenotypes associated with ASD have been identified and integrated into family genetic studies. In this review, we argue that advancing knowledge of the complex pathogenic processes that contribute to ASD can be accelerated by refocusing attention toward identifying endophenotypic traits reflective of inherited mechanisms. This pivot requires renewed emphasis on study designs with measurement of familial co-variation including infant sibling studies, family trio and quad designs, and analysis of monozygotic and dizygotic twin concordance for select trait dimensions. We also emphasize that clarification of endophenotypic traits necessarily will involve integration of transdiagnostic approaches as candidate traits likely reflect liability for multiple clinical conditions and often are agnostic to diagnostic boundaries. Multiple candidate endophenotypes associated with ASD likelihood are described, and we propose a new focus on the analysis of "endophenotype trait domains" (ETDs), or traits measured across multiple levels (e.g., molecular, cellular, neural system, neuropsychological) along the causal pathway from genes to behavior. To inform our central argument for research efforts toward ETD discovery, we first provide a brief review of the concept of endophenotypes and their application to psychiatry. Next, we highlight key criteria for determining the value of candidate endophenotypes, including unique considerations for the study of ASD. Descriptions of different study designs for assessing endophenotypes in ASD research then are offered, including analysis of how select patterns of results may help prioritize candidate traits in future research. We also present multiple candidate ETDs that collectively cover a breadth of clinical phenomena associated with ASD, including social, language/communication, cognitive control, and sensorimotor processes. These ETDs are described because they represent promising targets for gene discovery related to clinical autistic traits, and they serve as models for analysis of separate candidate domains that may inform understanding of inherited etiological processes associated with ASD as well as overlapping neurodevelopmental disorders.

The Clinical Implications of the Academic Performance of the Siblings of Individuals With Autism Spectrum Disorder

We all know that autism spectrum disorder (ASD) can affect academic performance. Many children with autism face different challenges at school. However, less attention is paid to the siblings of autistic children, who are at a high risk of ASD or the broad autism phenotype (BAP). Recent data also shows that many siblings of ASD children suffer from neurodevelopmental disorders, mental health problems as well as poor academic performance. This review will look at the possible etiologies of the poor school performance of autistic children's siblings, with an emphasis on the challenges they face. We will also highlight the clinical implications of these findings, and the possible solutions that can help this vulnerable group.

Characterizing Emotion Recognition and Theory of Mind Performance Profiles in Unaffected Siblings of Autistic Children

Emotion recognition skills and the ability to understand the mental states of others are crucial for normal social functioning. Conversely, delays and impairments in these processes can have a profound impact on capability to engage in, maintain, and effectively regulate social interactions. Therefore, this study aimed to compare the performance of 42 autistic children (Mage = 8.25 years, SD = 2.22), 45 unaffected siblings (Mage = 8.65 years, SD = 2.40), and 41 typically developing (TD) controls (Mage = 8.56 years, SD = 2.35) on the Affect Recognition (AR) and Theory of Mind (TOM) subtests of the Developmental Neuropsychological Assessment Battery. There were no significant differences between siblings and TD controls. Autistic children showed significantly poorer performance on AR when compared to TD controls and on TOM when compared to both TD controls and unaffected siblings. An additional comparison of ASD, unaffected sibling and TD control subsamples, matched on full-scale IQ, revealed no group differences for either AR or TOM. AR and TOM processes have received less research attention in siblings of autistic children and remain less well characterized. Therefore, despite limitations, findings reported here contribute to our growing understanding of AR and TOM abilities in siblings of autistic children and highlight important future research directions.

The broad autism phenotype in real-life: clinical and functional correlates of autism spectrum symptoms and rumination among parents of patients with autism spectrum disorder

OBJECTIVE

Increasing literature reported higher rates of psychiatric disorders in parents of children with autism spectrum disorder (ASD), as well as of autistic-like features in social and cognitive functioning. However, little attention has been paid to the association between autistic traits (AT) and global functioning in this population. The aim of the present work was to investigate clinical and functional correlates of AT among parents of ASD children, with a specific focus on ruminative thinking.

METHODS

One hundred and twenty parents of ASD children were assessed by the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the Adult Autism Subthreshold Spectrum (AdAS Spectrum), the Ruminative Response Scale (RRS), the Social and Occupational Functioning Assessment Scale (SOFAS).

RESULTS

Subjects with at least 1 psychiatric disorder (39.2%) showed significantly higher AdAS Spectrum and RRS scores. Subjects with a history of school difficulties and with language development alterations scored significantly higher on specific AdAS Spectrum domains. A significant negative correlation was found between SOFAS and AdAS Spectrum scores, as well as between SOFAS and RRS scores. AdAS Spectrum nonverbal communication domain score was identified has a statistically predictive variable for the presence of psychiatric disorders and lower SOFAS scores. Finally, we found a significant indirect effect of AdAS total score on SOFAS score, which was fully mediated by RRS total score.

CONCLUSIONS

AT in parents of ASD children seem to be associated with a higher vulnerability toward psychopathology and with a lower global functioning. Ruminative thinking may play a role in the relationship between AT and functional outcome.

Subjective Cognitive Impairment and the Broad Autism Phenotype

INTRODUCTION

Roughly 4% to 23% of the population embody stress prone personality and other traits characterizing a subclinical "broad autism phenotype" (BAP). Subjective cognitive impairment (SCI) among healthy elderly is associated with psychological distress leading us to predict BAP would be associated with SCI.

METHODS

The Autism Spectrum Quotient, a self-administered 50 item questionnaire, was completed by 419 consecutive members of the Arizona APOE Cohort who underwent neuropsychological testing every 2 years. SCI was assessed with self and informant versions of the Multidimensional Assessment of Neurodegenerative Symptoms (MANS) Questionnaire.

RESULTS

A total of 45 individuals scored in the BAP range, designated BAP+, and the rest were BAP-. At entry, both Multidimensional Assessment of Neurodegenerative Symptoms Questionnaire Self and Informant scores were higher in the BAP+ group (P<0.0001). After age 60, the BAP+ group had greater annual increases in Multidimensional Assessment of Neurodegenerative Symptoms Questionnaire Self scores (0.05 vs. 0.02; difference=0.03; 95% confidence interval, 0.004-0.05; P=0.02) yet there was no difference between groups in memory decline. Over ~10 years 33 individuals developed mild cognitive impairment: 4 in the BAP+ group (8.9%) and 29 in the BAP- group (7.8%), P=0.77.

DISCUSSION

Individuals who meet criteria for the BAP have escalating SCI with age, but no greater rate of memory decline or clinical progression to mild cognitive impairment.

Temporal Processing Instability with Millisecond Accuracy is a Cardinal Feature of Sensorimotor Impairments in Autism Spectrum Disorder: Analysis Using the Synchronized Finger-Tapping Task

To identify a specific sensorimotor impairment feature of autism spectrum disorder (ASD), we focused on temporal processing with millisecond accuracy. A synchronized finger-tapping task was used to characterize temporal processing in individuals with ASD as compared to typically developing (TD) individuals. We found that individuals with ASD showed more variability in temporal processing parameters than TD individuals. In addition, temporal processing instability was related to altered motor performance. Further, receiver operating characteristic (ROC) curve analyses indicated that altered temporal processing can be useful for distinguishing between individuals with and without ASD. These results suggest that instability of temporal processing with millisecond accuracy is a fundamental feature of sensorimotor impairments in ASD.

ADHD-related symptoms and attention profiles in the unaffected siblings of probands with autism spectrum disorder: focus on the subtypes of autism and Asperger's disorder

BACKGROUND

The presence of attention-deficit/hyperactive disorder (ADHD) symptoms and impaired attention performance are commonly noted in individuals with autism spectrum disorder (ASD). However, little is known about attention performance in their unaffected siblings. This study aimed to investigate the ADHD-related traits and attention performance in unaffected siblings of probands with autism and Asperger syndrome (AS), as well as the clinical correlates of ADHD-related traits.

METHODS

We assessed the intention, hyperactivity-impulsivity, and oppositional symptoms, and attention profiles of 199 probands with a diagnosis of ASD (122 autism, 77 AS), their unaffected siblings, and 196 typically developing controls (TD) by their parents' reports on the ADHD-related symptoms and the Connors' Continuous Performance Test (CCPT), respectively.

RESULTS

Compared to TD, unaffected siblings of ASD probands were more hyperactive/impulsive and oppositional, particularly unaffected siblings of AS probands. In CCPT, unaffected siblings of AS have intermediate levels of performance between probands with AS and TD on focused attention and sustained attention but were not statistically different from AS probands or TD in these attention profiles. In contrast, unaffected siblings of autism probands have significantly better CCPT performance when compared to autism probands but not to TD. In addition, stereotyped behaviors predicted ADHD-related traits in both sibling groups, but distinctive patterns of other correlates for ADHD-related traits were found between the two sibling groups.

CONCLUSIONS

This work suggested that unaffected siblings of AS, but not autism, have more hyperactive/impulsive traits and a trend of pervasive attention deficits assessed by CCPT which might serve as potential endophenotypes for genetic studies in AS.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01582256.

Atypical preference for infant-directed speech as an early marker of autism spectrum disorders? A literature review and directions for further research

Autism spectrum disorders (ASD) refer to a complex group of neurodevelopmental disorders causing difficulties with communication and interpersonal relationships, as well as restricted and repetitive behaviours and interests. As early identification, diagnosis, and intervention provide better long-term outcomes, early markers of ASD have gained increased research attention. This review examines evidence that auditory processing enhanced by social interest, in particular auditory preference of speech directed towards infants and young children (i.e. infant-directed speech - IDS), may be an early marker of risk for ASD. Although this review provides evidence for IDS preference as, indeed, a potential early marker of ASD, the explanation for differences in IDS processing among children with ASD versus other children remains unclear, as are the implications of these impairments for later social-communicative development. Therefore, it is crucial to explore atypicalities in IDS processing early on development and to understand whether preferential listening to specific types of speech sounds in the first years of life may help to predict the impairments in social and language development.

From molecules to neural morphology: understanding neuroinflammation in autism spectrum condition

Growing evidence points toward a critical role for early (prenatal) atypical neurodevelopmental processes in the aetiology of autism spectrum condition (ASC). One such process that could impact early neural development is inflammation. We review the evidence for atypical expression of molecular markers in the amniotic fluid, serum, cerebrospinal fluid (CSF), and the brain parenchyma that suggest a role for inflammation in the emergence of ASC. This is complemented with a number of neuroimaging and neuropathological studies describing microglial activation. Implications for treatment are discussed.

Theory of Mind Indexes the Broader Autism Phenotype in Siblings of Children with Autism at School Age

Subclinical variants of the social-communicative challenges and rigidity that define autism spectrum disorder (ASD) are known as the broader autism phenotype (BAP). The BAP has been conceptualized categorically (as specific to a subset of relatives of individuals with ASD) and dimensionally (as continuously distributed within the general population). The current study examined the compatibility of these two approaches by assessing associations among autism symptoms and social-communicative skills in young school-age children with ASD, children who have a sibling with ASD, and children without a sibling with ASD. Autism symptoms were associated with reduced Theory of Mind (ToM), adaptive skills, cognitive empathy, and language skills across the full sample. Reduced ToM was a core aspect of the BAP in the current sample regardless of whether the BAP was defined categorically (in terms of siblings of children with ASD who exhibited atypical developmental) or dimensionally (in terms of associations with autism symptoms across the entire sample). Early language skills predicted school-age ToM. Findings support the compatibility of categorical and dimensional approaches to the BAP, highlight reduced ToM as a core aspect of the school-age BAP, and suggest that narrative-based approaches to promoting ToM may be beneficial for siblings of children with ASD.

Broader Autism Phenotype in Siblings of Children with ASD--A Review

Although less pronounced, social, cognitive, and personality characteristics associated with autism spectrum disorders (ASD) may be present in people who do not meet ASD diagnostic criteria, especially in first-degree relatives of individuals with ASD. Research on these characteristics, referred to as broader autism phenotype (BAP), provides valuable data on potential expressions of autism-specific deficits in the context of family relations. This paper offers a review of research on BAP in siblings of individuals with ASD, focusing on reports regarding social, communication, and cognitive deficits, published from 1993 to 2014. The studies are divided into two groups based on participants’ age: papers on preschool and older siblings of individuals with ASD; and publications on infants at risk for ASD. On the basis of this review, suggestions are offered for further research and its significance for our understanding of the genetic determinants of autism.

Cognitive abilities in siblings of children with autism spectrum disorders

The aim of the present study was to assess the cognitive profiles of children with autistic spectrum disorder and of their healthy siblings (Siblings). With the term cognitive profile, we indicate the relationship extant among the values of verbal and performance subtests of the Wechsler Intelligence Scale. The conducted statistical analyses indicated that, although siblings showed a normal intelligent quotient and did not differ in this aspect from typically developing group, their cognitive profile was amazingly similar to that of their relatives affected by autism. A k-means clustering analysis on the values of single subtests further confirmed this result, showing a clear separation between typically developing children on the one side, and autistics and their siblings on the other. We suggest that the common cognitive profile observed in autistic children and their siblings could represent a marker of liability to autism and, thus, a possible intermediate phenotype of this syndrome.

A review of cognitive neuropsychiatry in the taxonomy of eating disorders: state, trait, or genetic?

A greater understanding of neuropsychological traits in eating disorders may help to construct a more biologically based taxonomy. The aim of this paper is to review the current evidence base of neuropsychological traits in people with eating disorders. Evidence of difficulties in set shifting, weak central coherence, emotional processing difficulties, and altered reward sensitivity is presented for people both in the acute and recovered phase of the illness. These traits are also seen in first degree relatives. At present there is limited research linking these neuropsychological traits with genetic and neuroanatomical measures. In addition to improving the taxonomy of eating disorders, neuropsychological traits may be of value in producing targeted treatments.

The broad autism phenotype questionnaire: prevalence and diagnostic classification

The Broad Autism Phenotype Questionnaire (BAPQ) was administered to a large community-based sample of biological parents of children with autism (PCAs) and comparison parents (CPs) (n = 1,692). Exploratory factor analysis and internal consistency parameters confirmed a robust three-factor structure of the BAPQ, corresponding to the proposed aloof, pragmatic language and rigidity subscales. Based upon the distribution of Broad Autism Phenotype (BAP) features in the general population, new normative cutoff values for BAPQ subscales were established that provide increased specificity relative to those previously reported, and thus enhance the utility of the BAPQ for diagnostically classifying the BAP. These cutoffs were also used to estimate prevalence of the BAP and its three components, with rates ranging between 14-23% for PCAs and between 5-9% for CPs. Analysis of patterns of BAP characteristics within family members revealed that BAP features were more likely to co-occur in PCAs relative to CPs. Collectively, these findings extend the utility of the BAPQ and provide additional evidence that it is an efficient and reliable tool for disaggregating the heterogeneity of autism through the identification of meaningful subgroups of parents. Autism Res 2013, 6: 134-143. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.

Failure to learn from feedback underlies word learning difficulties in toddlers at risk for autism

Children's assignment of novel words to nameless objects, over objects whose names they know (mutual exclusivity; ME) has been described as a driving force for vocabulary acquisition. Despite their ability to use ME to fast-map words (Preissler & Carey, 2005), children with autism show impaired language acquisition. We aimed to address this puzzle by building on studies showing that correct referent selection using ME does not lead to word learning unless ostensive feedback is provided on the child's object choice (Horst & Samuelson, 2008). We found that although toddlers aged 2;0 at risk for autism can use ME to choose the correct referent of a word, they do not benefit from feedback for long-term retention of the word-object mapping. Further, their difficulty using feedback is associated with their smaller receptive vocabularies. We propose that difficulties learning from social feedback, not lexical principles, limits vocabulary building during development in children at risk for autism.

Autistic traits below the clinical threshold: re-examining the broader autism phenotype in the 21st century

Diagnosis, intervention and support for people with autism can be assisted by research into the aetiology of the condition. Twin and family studies indicate that autism spectrum conditions are highly heritable; genetic relatives of people with autism often show milder expression of traits characteristic for autism, referred to as the Broader Autism Phenotype (BAP). In the past decade, advances in the biological and behavioural sciences have facilitated a more thorough examination of the BAP from multiple levels of analysis. Here, the candidate phenotypic traits delineating the BAP are summarised, including key findings from neuroimaging studies examining the neural substrates of the BAP. We conclude by reviewing the value of further research into the BAP, with an emphasis on deriving heritable endophenotypes which will reliably index autism susceptibility and offer neurodevelopmental mechanisms that bridge the gap between genes and a clinical autism diagnosis.

The broader autism phenotype and its implications on the etiology and treatment of autism spectrum disorders

The presence of autism-related traits has been well documented in undiagnosed family members of individuals with autism spectrum disorder (ASD). The most common finding is mild impairments in social and communication skills that are similar to those shown by individuals with autism, but exhibited to a lesser degree. Termed the broader autism phenotype (BAP), these traits suggest a genetic liability for autism-related traits in families. Genetic influence in autism is strong, with identical twins showing high concordance for the diagnosis and related traits and approximately 20% of all ASD cases having an identified genetic mechanism. This paper highlights the studies conducted to date regarding the BAP and considers the implications of these findings for the etiology and treatment of ASD.

Impaired ability to organize information in individuals with autism spectrum disorders and their siblings

Despite rigorous research on disturbances of executive function and social cognition in autism spectrum disorders (ASD), little information has been available concerning higher cognitive functions, such as the ability to focus and associate relevant features to form categories, or 'organizing of information'. The purpose of this study was to investigate this issue by using the Wisconsin Card Sorting Test (WCST) and the Verbal Learning Task (VLT). Cognitive assessments were conducted in 22 individuals with ASD, 14 non-affected siblings, and 15 age-matched control subjects. Overall, individuals with ASD performed significantly worse on the WCST and VLT compared to their siblings and normal control subjects. Although siblings performed generally well on both tasks, they exhibited similar degree of perseverative responses in the WCST compared to the probands. A linear increase of the memory organization score in the VLT was also absent in siblings as well as the ASD group. These results suggest an impaired ability to organize information is one of the cognitive endophenotypes for ASD.

Adults with autism spectrum disorders and ADHD neuropsychological aspects

The purpose of the present study was to assess which types of neuropsychological deficits appear to be most commonly associated with autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) in adults. The effect of the combination of ASD with ADHD (ASD/ADHD) was also studied. One hundred and sixty-one adult individuals (≥18 years of age) were included in the study. None had full scale IQ less than 71. The neuropsychological investigations included measures of intellectual ability, learning and memory, attention/executive function and theory of mind. The three diagnostic groups showed reduced performance in most cognitive domains. However, within these domains differentiating distinct features could be seen. The dysfunctions of the ASD/ADHD group cannot be seen as a summary of the dysfunctions found in the ASD and ADHD groups. The ADHD seemed to have the most severe neuropsychological impairments of the three groups. No domain-specific deficit typical of any of the diagnostic groups was found.

Broader autism phenotype and nonverbal sensitivity: evidence for an association in the general population

This study examined the relationship between characteristics of the Broader Autism Phenotype (BAP) and nonverbal sensitivity, the ability to interpret nonverbal aspects of communication, in a non-clinical sample of college students. One hundred and two participants completed a self-report measure of the BAP, the Autism Spectrum Quotient (AQ), and two tests of nonverbal sensitivity, the Test of Nonverbal Cue Knowledge (TONCK), and the Diagnostic Analysis of Nonverbal Accuracy 2 (DANVA2). AQ score was correlated with TONCK performance and number of errors on the adult faces subtest of the DANVA2, but not adult paralanguage or postures. These findings suggest that characteristics of ASD in the general population are associated with differences in both explicit and implicit knowledge of nonverbal cues.

Frontal cortex functioning in the infant broader autism phenotype

Atypical attention has been proposed as a marker of the broader autism phenotype. In the present study we investigated this and the related process of inhibitory control at the youngest possible age through the study of infant siblings of children with an autism spectrum disorder (Sibs-ASD). Both attention and inhibition have been related to the frontal cortex of the brain. Nine- to ten-month-old Sibs-ASD and low-risk control infants completed the Freeze-Frame task, in which infants are encouraged to inhibit looks to peripherally presented distractors whilst looking at a central animation. The attractiveness of the central stimulus is varied in order to investigate the selectivity of infants' responses. In line with previous studies, it was found that a subset of Sibs-ASD infants had difficulty disengaging attention from a central stimulus in order to orient to a peripheral stimulus. The Sibs-ASD group also showed less Selective Inhibition than controls. However, Sibs-ASD infants did demonstrate Selective Inhibitory Learning. These results provide preliminary evidence for atypical frontal cortex functioning in the infant broader autism phenotype.

Impaired prefrontal hemodynamic maturation in autism and unaffected siblings

Background

Dysfunctions of the prefrontal cortex have been previously reported in individuals with autism spectrum disorders (ASD). Previous studies reported that first-degree relatives of individuals with ASD show atypical brain activity during tasks associated with social function. However, developmental changes in prefrontal dysfunction in ASD and genetic influences on the phenomena remain unclear. In the present study, we investigated the change in hemoglobin concentration in the prefrontal cortex as measured with near-infrared spectroscopy, in children and adults with ASD during the letter fluency test. Moreover, to clarify the genetic influences on developmental changes in the prefrontal dysfunction in ASD, unaffected siblings of the ASD participants were also assessed.

Methodology/Principal Findings

Study participants included 27 individuals with high-functioning ASD, age- and IQ-matched 24 healthy non-affected siblings, and 27 unrelated healthy controls aged 5 to 39 years. The relative concentration of hemoglobin ([Hb]) in the prefrontal cortex was measured during the letter fluency task. For children, neither the [oxy-Hb] change during the task nor task performances differed significantly among three groups. For adults, the [oxy-Hb] increases during the task were significantly smaller in the bilateral prefrontal cortex in ASD than those in control subjects, although task performances were similar. In the adult siblings the [oxy-Hb] change was intermediate between those in controls and ASDs.

Conclusion/Significance

Although indirectly due to a cross-sectional design, the results of this study indicate altered age-related change of prefrontal activity during executive processing in ASD. This is a first near-infrared spectroscopy study that implies alteration in the age-related changes of prefrontal activity in ASD and genetic influences on the phenomena.

Developmental trajectories in siblings of children with autism: cognition and language from 4 months to 7 years

We compared the cognitive and language development at 4, 14, 24, 36, 54 months, and 7 years of siblings of children with autism (SIBS-A) to that of siblings of children with typical development (SIBS-TD) using growth curve analyses. At 7 years, 40% of the SIBS-A, compared to 16% of SIBS-TD, were identified with cognitive, language and/or academic difficulties, identified using direct tests and/or parental reports. This sub-group was identified as SIBS-A-broad phenotype (BP). Results indicated that early language scores (14-54 months), but not cognitive scores of SIBS-A-BP and SIBS-A-nonBP were significantly lower compared to the language scores of SIBS-TD, and that the rate of development was also significantly different, thus pinpointing language as a major area of difficulty for SIBS-A during the preschool years.

Neural mechanisms of empathy in adolescents with autism spectrum disorder and their fathers

A deficit in empathy has been repeatedly described in individuals with autism spectrum disorder (ASD) and also, albeit less markedly, in their unaffected relatives. Here, we aimed to investigate the neural mechanisms of empathy in ASD, and to explore familial contributions to empathy correlates. Using functional magnetic resonance imaging, 15 boys with ASD, 11 fathers of adolescents with ASD, and two control groups comparable for age and IQ (n=15 typically developing boys and their fathers (n=9)) were investigated during an empathy task. Emotional faces were presented and participants were either asked to infer the emotional state from the face (other-task) or to judge their own emotional response to the face (self-task). When attributing emotions to self and other, the ASD group showed diminished fusiform gyrus activation compared to controls. Neural activity in the fusiform gyrus was inversely related to social deficits in ASD subjects. Moreover, when ASD subjects inferred their own emotional response to faces, they showed less congruent reactions and inferior frontal gyrus activity was decreased. Although fathers of ASD children scored higher on a self-rating scale for autistic symptoms compared to control fathers, their task performance was unimpaired. However, neurally, fathers of affected children also showed reduced fusiform gyrus activation when inferring others' emotions. Shared abnormalities in fusiform gyrus activation in affected adolescents and first-degree relatives suggest that this dysfunction constitutes a fundamental deviation in ASD. Moreover, the findings provide evidence that both aberrant neural face and mirroring mechanisms are implicated in empathy impairments in ASD.

Research review: crossing syndrome boundaries in the search for brain endophenotypes

The inherent imprecision of behavioral phenotyping is the single most important factor contributing to the failure to discover the biological factors that are involved in psychiatric and neurodevelopmental disorders (e.g., Bearden & Freimer, 2006). In this review article we argue that in addition to an appreciation of the inherent complexity at the biological level, a rather urgent task facing behavioral scientists involves a reconsideration of the role that clinical syndromes play in psychological theorizing, as well as in research into the biological basis of cognition and personality. Syndrome heterogeneity, cross-syndrome similarities and syndrome comorbidities question the relevance of syndromes to biological research. It is suggested that the search for brain endophenotypes, intermediate between genes and behavior, should be based on cross-syndrome, trait classification. Cohort selection should rest on behavioral homogeneity, enabling, when necessary, syndrome heterogeneity.

Theory of mind and verbal working memory deficits in parents of autistic children

The objective of this study was to investigate the potential values of executive function and social cognition deficits as endophenotypes of autism. While theory of mind (ToM) is generally accepted as a unitary concept, some have suggested that ToM may be separated into two components (mental state reasoning and decoding). In this study, both aspects of ToM and verbal working memory abilities were investigated with relatively demanding tasks. The authors used a neurocognitive battery to compare the executive function and social cognition skills of 76 parents of autistic probands with 41 parents of healthy children. Both groups were matched for IQ, age and gender. Index parents had verbal working memory deficits. They had also low performance on a mental state reasoning task. Index parents had difficulties in reasoning about others' emotions. In contrast to findings in the control group, low performance of mental state reasoning ability was not associated with working memory deficit in index parents. Social cognition and working memory impairments may represent potential endophenotypes, related to an underlying vulnerability for autistic spectrum disorders.

A longitudinal study of executive function and theory of mind development in autism

Both executive function and theory of mind impairment have been suggested as primary deficits of autism. One test of the primacy of a deficit is its persistence and stability throughout development. This longitudinal study examined development of executive function and theory of mind abilities over a 3-year time period, comparing nonretarded autistic adolescents with learning-disabled controls matched on age, IQ, gender, and socioeconomic status (SES). Results indicate that both executive function and theory of mind abilities are seriously deficient in autistic individuals, improve little with development, may never reach normal functioning levels, and appear to eventually hit a developmental ceiling. Developmental variables showed little relationship to overall task performance or improvement in either cognitive domain. The similar developmental trajectories of executive function and theory of mind performance found in this investigation suggest that these skills may be related and interdependent, rather than independent modules of cognitive function. Implications for the neurological basis of autism and intervention are also discussed.

Current developments in the genetics of autism: from phenome to genome

Despite compelling evidence from twin and family studies indicating a strong genetic involvement in the etiology of autism, the unequivocal detection of autism susceptibility genes remains an elusive goal. The purpose of this review is to evaluate the current state of autism genetics research, with attention focused on new techniques and analytic approaches. We first present a brief overview of evidence for the genetic basis of autism, followed by an appraisal of linkage and candidate gene study findings and consideration of new analytic approaches to the study of complex psychiatric conditions, namely, genome-wide association studies, assessment of structural variation within the genome, and the incorporation of endophenotypes in genetic analysis.

Neuropsychological functioning of siblings of children with autism, siblings of children with developmental language delay, and siblings of children with mental retardation of unknown genetic etiology

Neuropsychological functioning of 30 siblings of children with autism (AU-S), 28 siblings of children with mental retardation of (MR-S), and 30 siblings of children with developmental language delay (DLD-S) was compared. Two siblings, both AU-S, received diagnoses of pervasive developmental disorder (PDD). More siblings with cognitive disabilities were found in DLD-S than in AU-S. However, these differences disappeared after excluding diagnosed siblings or after accounting for family membership. In sum, despite the elevated incidence of PDD among AU-S, the neuropsychological functioning of the remaining siblings did not convey specific characteristics related to the genetic risk associated with autism, in contrast to the cognitive functioning of the DLD-S, which did reflect a genetic risk.

Inhibitory control in children with autism spectrum disorder

Impairments in executive abilities such as cognitive flexibility have been identified in individuals with autism spectrum disorder (ASD). It remains unclear, however, whether such individuals also experience impairments in another executive ability: inhibitory control. In the present study, we administered three inhibitory tasks to 18 children with ASD, 23 siblings of children with ASD, and 25 typically developing children. After controlling for individual differences in age, overall IQ, and processing speed, children with ASD demonstrated impaired performance on two of the three inhibitory tasks. Results suggest that children with ASD experience circumscribed deficits in some but not all aspects of inhibitory control. More generally, the findings underscore the importance of using multiple measures to assess a putative single cognitive ability.

Cognitive and verbal abilities of 24- to 36-month-old siblings of children with autism

The cognitive and language skills of 30 siblings of children with autism (SIBS-A) and 30 siblings of typically developing children (SIBS-TD) were compared. Non-significant group differences emerged for cognition at both ages. At 24 months, significantly more SIBS-A demonstrated language scores one or two standard deviations below the mean compared to SIBS-TD. At 36 months, the groups differed significantly in receptive language, and more SIBS-A displayed receptive and expressive difficulties compared to SIBS-TD. Six SIBS-A (including one diagnosed with autism) revealed language scores more than two standard deviations below the mean at both ages, a pattern not seen in the SIBS-TD. Results are discussed in reference to language difficulties in autism spectrum disorders and the genetic liability for autism.

Social-cognition and the broad autism phenotype: identifying genetically meaningful phenotypes

BACKGROUND

Strong evidence from twin and family studies suggests that the genetic liability to autism may be expressed through personality and language characteristics qualitatively similar, but more subtly expressed than those defining the full syndrome. This study examined behavioral features of this 'broad autism phenotype' (BAP) in relation to performance on a measure of social-cognition in an attempt to tease out this complex clinical picture and identify markers of underlying neuropsychological systems of genetic significance to autism. We hypothesized that mild social-cognitive impairment would be associated with clinically defined social characteristics of the BAP (aloof personality style, lower quality social relationships, and impaired pragmatic language use).

METHOD

Forty-eight parents of individuals with autism (13 of whom were identified as 'aloof'), and 22 control parents, were administered the 'Eyes Test', a social-cognitive measure that taps the ability to read complex psychological states from viewing only the eye region of faces.

RESULTS

Whereas social-cognitive ability was unimpaired among parents of autistic children in general, the subgroup of parents defined as 'aloof' displayed significant social-cognitive deficits on the 'Eyes Test'. Impaired social-cognitive ability was associated with low quality of friendships and problems with pragmatic language use, associations which mirror those documented in autism.

CONCLUSIONS

Findings suggest that social-cognitive impairments co-segregate with conceptually related personality, social, and language features that constitute the BAP, and point towards performance on the Eyes Test as a genetically meaningful endophenotype.

Theory of mind abilities in young siblings of children with autism

Deficits in theory of mind (ToM), evident in most individuals with autism, have been suggested as a core deficit of autism. ToM difficulties in young siblings of children with autism (SIBS-A) compared to siblings of typically developing children (SIBS-TD) would place the former within the broad phenotype. We examined ToM's possible associations with measures of language, cognition, and daily living skills. Participants comprised 24 SIBS-A and 24 matched SIBSTD aged 4.6 years. They completed the false belief and the strange stories tasks. We also collected measures of verbal and cognitive ability and daily living skills. Non-significant differences emerged between the groups on both ToM tasks. Differences did emerge in within-group associations between ToM ability and receptive language. The conclusion is that SIBS-A show resilience in ToM abilities. Possibly, these deficits are not genetically transferred to siblings, at least as measured in laboratory-based ToM tasks.

Shared executive dysfunctions in unaffected relatives of patients with autism and obsessive-compulsive disorder

BACKGROUND

Executive dysfunctions have been studied as a potential endophenotype associated with the genetic basis of autism. Given that recent findings from clinical and molecular genetic studies suggest that autism and obsessive-compulsive disorder (OCD) could share a common pattern of heritability, we assessed executive functions as a possible common cognitive endophenotype in unaffected family members of individuals with either autism or OCD.

METHODS

Five tests assessing executive functions (Tower of London, verbal fluency, design fluency, trail making and association fluency) were proposed to 58 unaffected first-degree relatives (parents and siblings) of probands with autism and 64 unaffected first-degree relatives of OCD patients. Results were compared with those of 47 healthy controls matched for age, sex, and level of education.

RESULTS

In the Tower of London test, both groups of unaffected relatives showed significantly lower scores and longer response times compared with controls. No differences were observed between autism and OCD relatives and healthy controls in the four other tasks (verbal fluency, design fluency, trail making test and association fluency).

CONCLUSIONS

Our findings show the existence of executive dysfunction in the unaffected first-degree relatives of probands with OCD, similar to those observed in the relatives of patients with autism. These results support and extend previous cognitive studies on probands indicating executive dysfunctions in autism and OCD. Planning and working memory processes could thus represent a common cognitive endophenotype in autism and OCD that could help in the identification of genes conferring vulnerability to these disorders.

Profiles of executive function in parents and siblings of individuals with autism spectrum disorders

Delineation of a cognitive endophenotype for autism is useful both for exploring the genetic mechanisms underlying the disorder and for identifying which cognitive traits may be primary to it. This study investigated whether first-degree relatives of individuals with autism spectrum disorders (ASDs) demonstrate a specific profile of performance on a range of components of executive function (EF), to determine whether EF deficits represent possible endophenotypes for autism. Parents and siblings of ASD and control probands were tested on EF tasks measuring planning, set-shifting, inhibition and generativity. ASD parents showed poorer performance than control parents on a test of ideational fluency or generativity, and ASD fathers demonstrated a weakness in set-shifting to a previously irrelevant dimension. ASD siblings revealed a mild reduction in ideational fluency and a weakness in non-verbal generativity when compared with control siblings. Neither ASD parents nor siblings displayed significant difficulties with planning or inhibition. These results indicated that the broad autism phenotype may not be characterized primarily by impairments in planning and cognitive flexibility, as had been previously proposed. Weaknesses in generativity emerged as stronger potential endophenotypes in this study, suggesting that this aspect of EF should play a central role in cognitive theories of autism. However, discrepancies in the EF profile demonstrated by parents and siblings suggest that factors related to age or parental responsibility may affect the precise pattern of deficits observed.

The broader cognitive phenotype of autism in parents: how specific is the tendency for local processing and executive dysfunction?

BACKGROUND

The objective of this study was to investigate the tendency for local processing style ('weak central coherence') and executive dysfunction in parents of subjects with an autism spectrum disorder (ASD) compared with parents of individuals with early onset schizophrenia (EOS) and mental retardation (MR).

METHOD

Sixty-two parents of subjects with ASD, 36 parents of subjects with EOS and 30 parents of subjects with MR were examined. Data on two scales indicative of local visual processing (Embedded Figures Test, Block Design) and on three executive function tests (Wisconsin Card Sorting Test, Tower of Hanoi, Trailmaking Test) were collected for all participants.

RESULTS

Parents of subjects with ASD performed significantly faster on the Embedded Figures Test compared with both control samples. No other substantial group differences were observed.

CONCLUSIONS

The findings indicate that an increased tendency for local processing in terms of visual disembedding could be a relatively specific core feature of the broader cognitive phenotype of autism in parents.

Conducting genetic epidemiology studies of autism spectrum disorders: issues in matching

The objective of this review is to clarify the role of matching in family genetic studies of autism as a way of defining endophenotypes for linkage analysis. The concept of a confounding variable is reviewed and the importance of considering these in family studies of three endophenotypes in autism are considered: cognitive/language impairments, psychiatric disorders, and autistic-like traits. The importance of matching in infant sibling studies of autism is also addressed. Matching as a way of dealing with confounding variables has an important impact on understanding the extent to which these phenotypes are associated with the genes that confer susceptibility to autism and to the early detection of the disorder. Matching continues to be an important issue in the planning and conduct of family-genetic studies of the autism spectrum disorders, particularly as the search for autism susceptibility genes enters the next generation of studies.

An exploration of causes of non-literal language problems in individuals with Asperger Syndrome

Individuals with Asperger Syndrome (AS), a high functioning variant of Autism, are often noted to possess intact language ability, yet fail to use this language capacity to engage in interactive communication. This difficulty using language in a social context has been referred to as a deficit in pragmatic language. In particular, difficulty understanding nonliteral language devices, such as irony has been observed. This paper examines the veracity of two theories that have attempted to explain the causes of pragmatic language difficulties in individuals with Asperger Syndrome; the theory of Weak Central Coherence (WCC) and Social Inference theory. Fourteen young adults with AS and 24 age-matched controls were assessed on cognitive tasks measuring WCC processes, social inference or Theory of Mind ability, and the ability to interpret ironic remarks. Results indicated that the ability to understand the belief states of others is critical to understanding ironic language in AS.

Eye movement abnormality suggestive of a spatial working memory deficit is present in parents of autistic probands

Autistic probands exhibit impaired spatial accuracy and impaired response suppression errors during a delayed oculomotor response task. Family members of autistic probands, and thus the possible familial nature of these deficits, have not been assessed. Eleven parents of autistic probands and 17 adults from unaffected families, ages 25-50 years, completed oculomotor delayed-response tasks. Parents of autistic probands demonstrated poorer spatial accuracy than the comparison group (p = .002), with no significant differences between groups on percentage of premature saccades or latency of remembered saccades. Spatial working memory deficits, as measured by the delayed oculomotor response task, appear to be familial in families with an autistic proband. These deficits deserve further evaluation as a potential endophenotypic marker for genetic risk for autism.

Fringe phenotypes in autism: a review of clinical, biochemical and cognitive studies

Progress in identifying the genetic vulnerability factors in autism requires correct identification of the inherited phenotype(s). This can be achieved not only by the accurate description of the affected subject but also by the identification of vulnerability traits in non-affected relatives of autistic probands. This review will focus on this last strategy and principally on clinical, biochemical and cognitive traits.

Child clinical/pediatric neuropsychology: some recent advances

The neuropsychological assets and deficits of several types of pediatric neurological disease, disorder, and dysfunction are described. These are examined from the perspective of the syndrome of nonverbal learning disabilities (NLD) and the "white matter model" designed to explain its complex manifestations. It is concluded that children with some of these diseases exhibit the NLD phenotype, whereas others do not. For the most part, the diseases in which the NLD phenotype is particularly evident are those wherein it has been demonstrated that perturbations of white matter (long myelinated fibers) are particularly prominent.

Executive function deficits in non-retarded autistic children

The purpose of this study was to examine differences between Taiwanese children with autism and their typically developing peers on the Wisconsin Card Sorting Test (WCST). Twenty-six children with autism of normal IQ were included, and matched for chronological age with 52 controls. The WCST scores of the typically developing children were significantly higher for categories completed and percent conceptual level than in the autism group. Scores on perseverative responses, perseverative errors, the number of trials to complete the first category and non-perseverative errors were significantly higher in the autism group. The implications of these findings are discussed.