The effects of gender and age on repetitive and/or restricted behaviors and interests in adults with autism spectrum disorders and intellectual disability

► Repetitive and restrictive behaviors occur at high rates in persons with severe or profound intellectual disability and autism. ► Males in this study had higher rates of repetitive and restrictive behaviors than females. ► The rates of repetitive and restrictive behaviors were similar for young and older adults. ► Identifying rates and intensities of core symptoms of autism and co-occurring problems are very important for treatment planning. Frequency of repetitive and/or restricted behaviors and interests (RRBIs) was assessed in 140 adults with autism spectrum disorders (ASDs) and severe or profound intellectual disability (ID). The associations of gender and age range were analyzed with RRBI frequency which was obtained using the Stereotypies subscale of the Diagnostic Assessment for the Severely Handicapped-II ( DASH-II). A significant main effect of gender was found. Male participants had higher frequency of RRBIs than females regardless of age range. There was not a significant main effect of age range or a significant interaction between gender and age range. Results and implications are discussed.