Behavioral problems in children with autism spectrum disorder with and without co-occurring intellectual disability

Background: Autism spectrum disorder (ASD), intellectual disability (ID), and behavioral problems commonly co-occur, leading to increased impairment, diagnostic confusion, and treatment delays. Using data from a large surveillance population of children with ASD, the objectives of the present study were to compare the relative risk of common behavioral problems in children with ASD, with and without co-occurring intellectual disability. Methods: Data from the Autism and Developmental Disabilities Monitoring (ADDM) Network (2006–2010) on 9378 8-year-old children who met case definition for ASD and had cognitive test scores and information on behavioral problems were analyzed using frequency measures, risk ratios, chi-squared tests, and trend tests. Results: Children with ASD with and without ID had on average six co-occurring behavioral problems. The relative risk (RR) of self-injurious behaviors, unusual fear responses, and eating abnormalities increased with increasing cognitive impairment among children with ASD and ID (all p<0.001). Conversely, RR of mood (p<0.001) and sleep abnormalities (p=0.013) declined with increasing levels of cognitive impairment. Conclusions: Children with ASD and ID are at greater risk of some behavioral problems and lower risk of others as compared to children with ASD only. Successful interventions depend on understanding the complex interactions between co-occurring neurodevelopmental and behavioral problems.