Association of cognitive and adaptive skills with internalizing and externalizing problems in autistic children and adolescents

The presence of an intellectual disability (ID) alongside autism is considered to increase the risk for mental health and behavior problems in children and adolescents. Existing evidence is restricted by looking at ID as a categorical classification. The study aimed to examine the association of cognitive and adaptive behavior skills with internalizing and externalizing problems in a large sample of autistic children and adolescents, across a wide range of cognitive skills. Participants were 2759 children and adolescents aged between 4 and 18 years recruited as part of the Simons Simplex Collection (SSC), of whom 709 (approximately 25%) had ID. Multiple regression models examined associations of internalizing and externalizing problems with cognitive and adaptive skills (communication, daily living, and socialization skills). Cognitive skills were not associated with externalizing problems but were associated with more internalizing problems in autistic children without ID (Cog beta: 0.126). All adaptive skill domains were inversely associated with externalizing (Communication beta: -0.145; Daily-Living beta: -0.132; Socialization beta: -0.289) and internalizing problems (Communication beta: -0.074; Daily-Living beta: -0.064; Socialization beta: -0.213) in those without ID. Daily living (beta: -0.158) and socialization skills (beta: -0.104) were inversely correlated with externalizing problems in autistic children with ID, while only socialization problems (beta: -0.099) were associated with internalizing problems in this group. Socialization skills were systematically associated with internalizing and externalizing problems across all levels of cognitive functioning. Supporting social skills development may benefit all aspects of child mental health, while recognizing that children with higher cognitive skills are more vulnerable to internalizing problems might assist with earlier identification of these problems. Autistic youth are very likely to experience high levels of emotional problems (often called internalizing problems) or difficulties with their behavior (often called externalizing problems). In this study, we investigated whether internalizing and externalizing difficulties are related to cognitive functioning and skills needed in daily life. Cognitive functioning was not associated with externalizing problems in autistic children and adolescents, whether they also had an intellectual disability or not. However, in autistic children without intellectual disability, higher cognitive functioning related to increased internalizing problems. Poorer social skills were associated with increased internalizing and externalizing problems for all participants. Autistic youth without an intellectual disability may be more vulnerable to internalizing problems. Autistic youth who experience more difficulties in their social interactions may be more vulnerable to internalizing and externalizing difficulties whether they have an intellectual disability or not.