Repetitive and Restricted Behaviors and Interests in Autism Spectrum Disorder: Relation to Psychopathology

Repetitive and restricted behaviors and interests (RRBIs) in Autism Spectrum Disorder (ASD) have significant negative impacts on well-being and daily functioning. RRBIs vary as a function of an individual’s sex, age, and cognitive level as well as the presence of comorbid psychopathology. However, findings on these relationships have been ambiguous, partly due to the use of broad categorizations of RRBIs (e.g., lower- vs higher-order) rather than specific RRBIs (e.g., stereotypy) and the use of age-corrected cognitive level (i.e., IQ). The purpose of this study was to examine the patterns of specific RRBIs, obtained via the Repetitive Behavior Scale–Revised (RBS-R), in different sex, age, and raw cognitive level groups, as well as the relationship of RRBIs with internalizing and externalizing behaviors. Secondary data analyses were conducted using the Simons Simplex Collection (SSC) dataset, which included 2,758 participants ranging in age from 4 to 18 years. Across all RBS-R subtypes, results revealed no sex differences. However, older children demonstrated higher rates of Ritualistic/Sameness behaviors than younger children and adolescents, whereas younger and older children showed more Stereotypy than adolescents. In terms of cognitive level differences, the lower cognitive level groups showed higher rates of RBS-R subtypes except for Ritualistic/Sameness. After controlling for age and cognitive level, RBS-R subtypes accounted for a substantial amount of variance in internalizing and externalizing behaviors (23% and 25%, respectively). Specifically, Ritualistic/Sameness and Self-Injurious Behavior both predicted internalizing and externalizing behaviors, whereas Stereotypy only predicted internalizing behavior. These findings have key clinical implications that emphasize not only the consideration of sex, age, and cognitive level, but also specific RRBIs and associated psychopathology, when assessing for ASD and designing individualized interventions. Limitations of the present study and future directions are discussed.