Kristen S.L. Lam

Evidence for three subtypes of repetitive behavior in autism that differ in familiality and association with other symptoms

BACKGROUND Restricted repetitive behaviors (RRBs) are a core feature of autism and consist of a variety of behaviors, ranging from motor stereotypies to complex circumscribed interests. The objective of the current study was to examine the structure of RRBs in autism using relevant items from the Autism Diagnostic Interview-Revised in a sample of 316 individuals with autistic disorder. METHODS/RESULTS Using exploratory factor analysis, three distinct factors were identified: Repetitive Motor Behaviors (RMB), Insistence on Sameness (IS), and Circumscribed Interests (CI). RMB were found to be associated with a variety of subject characteristics such as IQ, age, social/communication impairments, and the presence of regression. IS was associated with social and communication impairments whereas CI appeared to be independent of subject characteristics, suggesting CI may be particularly useful in subsetting samples. Based on sib-pair correlations, IS and CI (but not RMB) appear to be familial. Analysis of the data at the case level suggests that the presence of multiple forms of RRB in an individual is associated with more impairment in the social and communication domains, suggesting a more severe presentation of autistic disorder. CONCLUSIONS There appears to be considerable structure within repetitive behavior in autism. The finding that these behaviors are differentially related to subject characteristics and familiality adds to their validity.

Age-Related Differences in Restricted Repetitive Behaviors in Autism Spectrum Disorders

Restricted repetitive behaviors (RRBs) were examined in a large group of children, adolescents and adults with ASD in order to describe age-related patterns of symptom change and association with specific contextual factors, and to examine if the patterns of change are different for the various types of RRBs. Over 700 individuals with ASD were rated on the Repetitive Behavior Scale-Revised. RRBs were less frequent and less severe among older than younger individuals, corroborating that autism symptoms abate with age. Our findings further suggest that repetitive behaviors are a heterogeneous group of behaviors, with the subtypes of RRBs having their own individual patterns across the lifespan, and in some cases, a differential association with age depending on intellectual functioning.

Defining key features of the broad autism phenotype: A comparison across parents of multiple- and single-incidence autism families

This study examined the frequency of personality, language, and social‐behavioral characteristics believed to comprise the broad autism phenotype (BAP), across families differing in genetic liability to autism. We hypothesized that within this unique sample comprised of multiple‐incidence autism families (MIAF), single‐incidence autism families (SIAF), and control Down syndrome families (DWNS), a graded expression would be observed for the principal characteristics conferring genetic susceptibility to autism, in which such features would express most profoundly among parents from MIAFs, less strongly among SIAFs, and least of all among comparison parents from DWNS families, who should display population base rates. Analyses detected linear expression of traits in line with hypotheses, and further suggested differential intrafamilial expression across family types. In the vast majority of MIAFs both parents displayed BAP characteristics, whereas within SIAFs, it was equally likely that one, both, or neither parent show BAP features. The significance of these findings is discussed in relation to etiologic mechanisms in autism and relevance to molecular genetic studies.

Children with autism demonstrate circumscribed attention during passive viewing of complex social and nonsocial picture arrays

Although circumscribed interests are a hallmark characteristic of autism spectrum disorders, providing a means for quantifying their functional impairment has proven difficult. We developed a passive viewing task to measure aspects of visual attention in children with autism spectrum disorders and typically developing controls. Task stimuli included picture arrays that were matched for social and nonsocial content. Nonsocial content was balanced to include items related to circumscribed interests (e.g., trains) as well as more commonplace items (e.g., furniture). Discrete aspects of gaze behavior were quantified using eye‐tracking technology. Results indicate that visual attention in the autism group was more circumscribed (as indicated by the exploration of fewer images), more perseverative (as indicated by longer fixation times per image explored), and more detail oriented (as indicated by a greater number of discrete fixations on explored images). This pattern of results was similar for both social and object arrays. Within the autism group, overall severity of repetitive behavior symptoms correlated positively with exploration of object pictures and negatively with perseveration on social pictures. Results suggest that children with autism have a domain‐general pattern of atypical visual attention that may represent an exaggeration of a typical attentional process and is related to a tendency to perseverate on images of interest and explore them in a more detail‐oriented manner. Discrete measures of visual attention may therefore provide a reasonable means of quantifying aspects of the repetitive behavior phenotype in autism.

Prevalence and Patterns of Use of Psychoactive Medicines Among Individuals with Autism in the Autism Society of Ohio

To date, there have been few surveys of psychotropic and antiepileptic drug (AED) prevalence in individuals with autism-spectrum conditions. We surveyed 747 families in the Autism Society of Ohio regarding the use of psychotropic drugs, AEDs, and over-the-counter (OTC) preparations for autism. In all, 417 families (55.8%) replied. A total of 45.6% were taking some form of psychotropic agent (including St. Johns wort and melatonin), whereas 11.5% were taking AEDs, and 10.3% took OTC autism preparations. The most common psychotropic agents included antidepressants (21.6%), antipsychotics (14.9%), antihypertensives (12.5%), and stimulants (11.3%). Some 51.6% were prescribed psychotropic drugs or AEDs, and 55.4% took psychotropic drugs, AEDs, or autism supplements. Demographic variables frequently found to be associated with medication use included greater age, more severe autism, more severe intellectual handicap, and housing outside the family home. Whereas there is empirical support for the use of some of these psychotropic agents in autism, others are being prescribed with minimal research support. OTC autism preparations were used in substantial numbers of individuals, despite limited research support and the possibility of toxic effects.

Phenomenology and measurement of circumscribed interests in autism spectrum disorders

Circumscribed interests (CI) are important and understudied symptoms that affect individuals with autism spectrum disorders (ASD). The present study sought to develop quantitative measures of the content, intensity and functional impairment of CI in 50 children with high-functioning ASD compared to an age-, IQ-, and gender-matched sample of 50 typically developing (TD) peers. The Interests Scale, a parent-rating questionnaire, and the Interview for Repetitive Behaviors, a semi-structured interview, were used to assess CI. Groups did not differ on the number of interests children held, but they did differ on types of interests and impairment associated with them. The interests of ASD participants were more likely to be nonsocial in nature (e.g. mechanical systems) than TD participants. Parents of children with ASD endorsed higher degrees of functional impairment on metrics including frequency, interference, resistance when interrupted, flexibility, and accommodation required, as well as less involvement of other people, than parents of children with TD. These findings suggest that interests of individuals with ASD differ qualitatively and in intensity from individuals with TD. The present study offers further support for the notion that CI reflect a clinically significant feature of ASD that warrants intervention in some children.

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.

Autism and the broad autism phenotype: familial patterns and intergenerational transmission

BackgroundFeatures of the Broad Autism Phenotype (BAP) are disproportionately prevalent in parents of a child with autism, highlighting familial patterns indicative of heritability. It is unclear, however, whether the presence of BAP features in both parents confers an increased liability for autism. The current study explores whether the presence of BAP features in two biological parents occurs more frequently in parents of a child with autism relative to comparison parents, whether parental pairs of a child with autism more commonly consist of one or two parents with BAP features, and whether these features are associated with severity of autism behaviors in probands.MethodSeven hundred eleven parents of a child with an autism spectrum disorder and 981 comparison parents completed the Broad Autism Phenotype Questionnaire. Parents of a child with autism also completed the Social Communication Questionnaire.ResultsAlthough parental pairs of a child with autism were more likely than comparison parental pairs to have both parents characterized by the presence of the BAP, they more commonly consisted of a single parent with BAP features. The presence of the BAP in parents was associated with the severity of autism behaviors in probands, with the lowest severity occurring for children of parental pairs in which neither parent exhibited a BAP feature. Severity did not differ between children of two affected parents and those of just one.ConclusionsCollectively, these findings indicate that parental pairs of children with autism frequently consist of a single parent with BAP characteristics and suggest that future studies searching for implicated genes may benefit from a more narrow focus that identifies the transmitting parent. The evidence of intergenerational transmission reported here also provides further confirmation of the high heritability of autism that is unaccounted for by the contribution of de novo mutations currently emphasized in the field of autism genetics.

Performance of Children with Autism Spectrum Disorders on the Dimension-Change Card Sort Task.

Restricted and repetitive behaviors in autism spectrum disorders have been conceptualized to reflect impaired executive functions. In the present study, we investigated the performance of 6–17-year-old children with and without an autism spectrum disorder on a dimension-change card sort task that explicitly indicated sorting rules on every trial. Diagnostic groups did not differ in speed of responses after the first rule switch or in speed or accuracy on blocks with mixed versus single sort rules. However, performance of the ASD group was significantly slower and less accurate overall than the typically-developing group. Furthermore, within the ASD group, poorer DCCS task performance did not predict more severe autism symptoms. Implications for the executive dysfunction theory of autism are discussed.

Generativity abilities predict communication deficits but not repetitive behaviors in Autism Spectrum Disorders.

Individuals with Autism Spectrum Disorders (ASD) often demonstrate impaired generativity that is thought to mediate repetitive behaviors in autism (Turner in J Child Psychol Psychiatry, 40(6):839–849, 1999a). The present study evaluated generativity in children with and without ASD via the use-of-objects task (Turner in J Child Psychol Psychiatry, 40(2):189–201, 1999b) and an Animals Fluency Task (Lezak in Neuropsychological assessment. Oxford University Press, Oxford, 1995). Groups differed significantly on two of four metrics from the Animals Fluency Task and two of seven metrics from the Use of Objects task. In the ASD sample, no significant relations were found between generativity and repetitive behaviors. Significant relations were found, however, between performance on the Animals Fluency Task and communication symptoms. Results replicate reports of generativity deficits in ASD and suggest that impaired generativity may reflect communication deficits that are characteristic of the disorder.