Predictors of individual differences in language in youth with Down Syndrome and Autism Spectrum Disorder

Background: Language is a major impairment in both Down syndrome and autism spectrum disorder (ASD), and thus, has a profound impact on everyday abilities. Research has explored the neurocognitive associates of language and has identified executive function (EF) and social abilities as domains associated with language. However, research has yet to identify these relations using parent report or examine them within the context of broader structural and pragmatic language abilities, two overarching domains of language. The current study utilizes informant report measures to examine the relations between these two domains of language and executive and social functioning. As findings in the literature on sex differences in language are mixed, the current study also sought to examine whether language varied as a function of sex. Method: Participants included 68 individuals with Down syndrome (Mage = 12.9) and 108 youth with autism spectrum disorder (Mage = 7.6). Participants completed parent reports of language, using the Children’s Communication Checklist-II, EF, using the Behavior Rating Inventory of Executive Functioning, and social abilities, measured by the Vineland Adaptive Behavior Scale or the Adaptive Behavior Assessment System. Results: Social abilities predicted structural language, and both EF and social abilities predicted pragmatic language in Down syndrome. In autism spectrum disorder, social and executive functioning predicted both structural and pragmatic language. Finally, sex differences were found in Down syndrome (males