Structure of Restricted Repetitive Behaviors of Individuals Referred for Autism Spectrum Disorder Assessment.

Abstract

Purpose: Restricted and/or repetitive displays of behavior, interests, or activities (RRBs) are one of the core symptom domains of autism spectrum disorder (ASD). Current and past research indicates two 'clusters' of RRBs in children with ASD: repetitive sensorimotor (e.g., hand/finger and more complex motor mannerisms) and insistence on sameness (e.g., resistance to changes in the environment) behaviors. The current study aims to fill a gap by examining how RRBs may diverge in individuals with ASD and with other neurodevelopmental disorders (ONDD) in a clinical sample.

Methods: A total of 558 individuals were seen at a tertiary care clinic for a comprehensive clinical assessment of ASD. The sample was split into ASD (n = 292 individuals) and ONDD (n = 266) groups based on clinical diagnosis. Exploratory factor analyses were conducted using Autism Diagnostic Interview-Revised (ADI-R) RRB item scores for the overall sample, the ASD group, and the ONDD group.

Results: Exploratory factor analysis of ADI-R RRB items indicated a 2-factor solution for the full sample and ASD group. Items loaded onto two factors comprised of "Repetitive Sensorimotor" and "Insistence on Sameness" behaviors, consistent with previous literature. Results demonstrated a unique loading pattern for the non-ASD group, with items clustering into "Higher Order" (e.g., circumscribed interests) and "Lower Order" (e.g., hand and finger mannerisms) behaviors.

Conclusion: The results of the current study may point towards using RRBs to guide screening of children who are referred for an ASD evaluation to better identify children who are at higher risk of having ASD.