Although repetitive behaviors are a core diagnostic domain for autism spectrum disorders, research in this area has been neglected. This study had two major aims: (1) to provide a detailed characterization of repetitive behaviors in individuals with Asperger Syndrome (AS), high-functioning autism (HFA), and typically developing controls (TD); and (2) to examine whether differences in repetitive behavior profiles could provide evidence for the external validity of AS separate from HFA. Specifically, it was hypothesized that circumscribed interests would be more prevalent and cause more impairment in the AS group than the HFA group, while the reverse would be true for other categories of repetitive behavior. The parent(s) of 61 children and adolescents (19 with AS, 21 with HFA, and 21 TD) completed two interviews focused specifically on lifetime and current repetitive behavior symptoms. No reliable differences in repetitive behavior between AS and HFA children were found. Results suggested that circumscribed interests differ in developmental course from the three other DSM-IV-TR categories of repetitive behavior. Internal consistency among the four DSM-IV-TR categories of repetitive behavior was high, alpha = .84, providing evidence for a unitary repetitive behaviors factor. The importance of expanding research in the repetitive behavior domain is highlighted as part of the necessary integration of behavioral and neurobiological approaches to understanding the etiology of autism.

Sensory processing abnormalities, anxiety and restricted and repetitive behaviours (RRBs) frequently co-occur in autism spectrum disorders (ASD). Though the relationship between these phenomena is not well understood, emerging evidence indicates intolerance of uncertainty (IU) may play an important role. This study aimed to determine pathways between sensory abnormalities and RRBs, and the role anxiety and IU may have. We gathered caregiver report data for 53 children with ASD aged 8-16 years. We found sensory under responsiveness and sensory over responsiveness were significantly associated with repetitive motor and insistence on sameness behaviours, and the relationships significantly mediated by IU and anxiety. Our findings indicate different mechanisms may underpin repetitive motor and insistence on sameness RRBs, which can inform treatment interventions.

Anxiety is a problem for many children diagnosed with autism spectrum disorders (ASDs). There is a paucity of models of the cognitive processes underlying this. Intolerance of uncertainty (IU) has utility in explaining anxiety in neurotypical populations but has only recently received attention in ASD. We modelled the relationship between anxiety and IU in ASD and a typically developing comparison group, using parent and child self-report measures. Results confirmed significant relationships between IU and anxiety in children with ASD which appears to function similarly in children with and without ASD. Results were consistent with a causal model suggesting that IU mediates the relationship between ASD and anxiety. The findings confirm IU as a relevant construct in ASD.

Severe symptoms of anxiety add substantial additional burden to many individuals diagnosed with Autism Spectrum Disorder (ASD). Improved understanding of specific factors that contribute to anxiety in ASD can aid research regarding the causes of autism and also provide targets for more effective intervention. This mini-review article focuses on emerging evidence for three concepts that appear to be related to each other and which also strongly predict anxiety in ASD samples. Atypical sensory function is included in the diagnostic criteria for ASD and is likely an important contributor to anxiety. Difficulties in understanding and labeling emotions (alexithymia), although a co-morbidity, may arise in part from atypical sensory function and can lead to confusion and uncertainty about how to respond to social and emotional situations. Intolerance of uncertainty (IU) describes people who have a particularly hard time with ambiguity and is known to be a key mechanism underlying some anxiety disorders. While evidence for linking these ideas is to date incomplete, we put forward a model including each concept as a framework for future studies. Specifically, we propose that IU is a critical mediator for anxiety in ASD, and explore the relationships between sensory function, alexithymia and IU. We further explore the role of the medial prefrontal cortex (mPFC) in regulating emotional response, in connection with limbic and insula-based networks, and suggest that disrupted integration in these networks underlies difficulties with habituation to strong emotional stimuli, which results in an enhanced perception of threat in many people with ASD. Behavioral and biologically-based treatments for anxiety in ASD will benefit from attending to these specific mechanisms as adjunct to traditional interventions.

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