Restricted and repetitive behaviors (RRBs) have long been considered one of the core characteristics of autism. RRBs include a very broad category of behaviors such as preoccupation with restricted patterns of interest (e.g. having very specific knowledge about vacuum cleaners), adherence to specific, nonfunctional routines (e.g. insisting on taking a certain route to school), repetitive motor manners (e.g., hand flapping), and preoccupation with parts of objects (e.g. peering at the wheels of toy cars while spinning them). Most research on RRBs has used caregiver reports either through interviews or questionnaires; thus, the purpose of this study was to use clinicians’ observations of RRBs, made during the Autism Diagnostic Observation Schedule (ADOS: Lord, Rutter, DiLavore & Risi, 2000) to discover how RRBs change over time in very young children who may have ASD and what other factors are related to having RRBs. The ADOS is a 45 minute long, semi-structured, standardized assessment of communication, social interaction and play, which was administered to 121 children with autism, 71 with pervasive developmental disorders-not otherwise specified (PDD-NOS), 90 with a nonspectrum disorder, and 173 children who were typically developing. Even during a relatively short-term observation in the context of an office visit, we found that RRBs occurred more frequently and were more severe in young children with autism and PDD-NOS diagnoses than children in other groups. Diagnostic group differences also emerged in the associations between RRB scores and participant characteristics (e.g. age, NVIQ scores, etc). We also examined different subtypes of RRBs and their associations with NVIQ, age, diagnosis, and gender.
Restricted and repetitive behaviors (RRBs) observed during the Autism Diagnostic Observation Schedule (ADOS: Lord, Rutter, DiLavore & Risi, 2000) were examined in a longitudinal dataset of 455 toddlers and preschoolers (age 8–56 months) with clinical diagnosis of Autism Spectrum Disorders (ASD; autism, n = 121 and pervasive developmental disorders-not otherwise specified (PDD-NOS), n = 71), a nonspectrum disorder (NS; n = 90), or typical development (TD; n = 173). Even in the relatively brief semi-structured observations, Generalized Estimating Equations (GEE) analyses of the severity and prevalence of RRBs differentiated children with ASD from those with NS and TD across all ages. RRB total scores on the ADOS were stable over time for children with ASD and NS; however, typically developing preschoolers showed lower RRB scores than typically developing toddlers. Nonverbal IQ (NVIQ) was more strongly related to the prevalence of RRBs in older children with PDD-NOS, NS and TD than younger children under 2 years and those with autism. Item analyses revealed different relationships between individual items and NVIQ, age, diagnosis, and gender. These findings are discussed in terms of their implications for the etiology and treatment of RRBs as well as for the framework of ASD diagnostic criteria in future diagnostic systems.