The Development of Restricted and Repetitive Behaviors and Interests in Children with Autism Spectrum Disorders.

Abstract

The development of restricted and repetitive behaviors and interests (RRBs) in Autism Spectrum Disorders (ASD) is examined in a series of three studies. In all studies, RRBs were assessed using the Autism Diagnostic Interview – Revised (ADI-R), a parent interview.

The first study considers RRBs in young children with ASD. Most RRBs were significantly more common in children with ASD than in children with nonspectrum developmental disorders (DD) and typical development (TD). A factor analysis supported the notion of RRB subtypes, one comprised of ‘repetitive sensorimotor’ (RSM) behaviors and the other of ‘insistence on sameness’ (IS) behaviors Having several RSM behaviors to a severe degree distinguished children with ASD from children with DD. IS behaviors were relatively uncommon in ASD at this age.

The second paper explores how RRBs change in children with ASD over time. For children with ASD, total RSM scores tended to remain relatively high over time, indicating consistent severity, whereas total IS scores started low and increased over time, indicating worsening. For the RSM behaviors, having a higher NVIQ and milder ASD were associated with improvement. NVIQ was not associated with IS trajectories, but milder social impairment was associated with more severe trajectories of IS scores, supporting the idea that these are ‘higher order’ behaviors.

Finally, the third paper examines the stability of RRBs over time. Scores on the RSM items tended to remain high over time, particularly for children with autism and/or lower NVIQ scores. Children who did not have RSM behaviors at a young age tended to acquire them over time. Conversely, scores on IS behaviors increased over time. Compared to the RSM behaviors, children who had IS behaviors at one point in development were not as likely to maintain them, but children who did not have these behaviors were more likely to continue not to have them. Children who gained behaviors in one subtype were the most likely to gain behaviors in the other.

The findings from this series of studies are discussed in terms of their implications for our understanding of the etiology and treatment of RRBs in ASD.