Internalizing and externalizing behaviors and close relationships in siblings of adolescents with autism spectrum disorder

The literature on typically developing (TD) siblings of individuals with Autism Spectrum Disorder (ASD-TD siblings) has grown over the last few decades, providing inconsistent results. Much attention has been reserved to sibling relationships when one shows ASD symptoms. The purpose of the current study was to examine the mutual influences between ASD-TD siblings’ emotional and behavioral characteristics, as evaluated by mothers, and the different dimensions of the sibling relationship through the lens of the behavioral system model. Specifically, the role of ASD-TD siblings’ emotional and behavioral functioning on sibling relationship was investigated. We hypothesized that the presence of internalizing and externalizing behaviors in ASD-TD siblings may be associated with less support, more negative interactions, and conflict in the sibling relationship. The sample included 59 ASD-TD siblings (35 M and 24 F; age range: 11–18 years, M = 14.20, SD = 1.52) of adolescents with ASD and their mothers. Behavioral and emotional characteristics of ASD-TD siblings showed significant associations with sibling relationship dimensions. Specifically, support was negatively and significantly related to externalizing behavior, whereas conflict was positively related to internalizing behavior. Additionally, externalizing and internalizing behaviors showed a predictive role: Externalizing behavior emerged as a significant negative predictor of support and internalizing behavior emerged as a significant positive predictor of negative interaction.