The interplay of language on executive functions in children with ASD

Autism Spectrum Disorder (ASD) is a neurodevelopmental disability characterized by deficits in social interaction and communication and by repetitive behaviors and restricted interests. Prior research has revealed executive function (EF) deficits in children with ASD. It has been suggested that these EF impairments are associated with language deficits intrinsic to ASD, specifically the inability to utilize inner speech to regulate non-routine behaviors (Russell, Jarrold, & Hood, 1999). Other studies, however, have found no link between language ability and EF (Joseph, McGrath, & Tager-Flusberg, 2005). The present study seeks to clarify the link between language and EF deficits in children with ASD in a cognitively heterogeneous sample. Four specific domains of EF (Working Memory, Organization, Shift, and Inhibition) were assessed in 62 children with ASD using direct measures (DKEFS, NEPSY, and WISC), and indirect parent/teacher report (BRIEF). Analysis by stepwise regressions showed measures of language skill, nonverbal cognition, and autistic symptom severity to be predictive of several domains of EF. Direct measure of Working Memory (WM) was predicted by structural and pragmatic language ability, direct measure of Organization (O) was predicted by nonverbal cognition, and direct measure of Shift (S) was predicted by nonverbal cognition and autistic symptom severity. Additionally, parent and teacher reports of WM were predicted by structural and pragmatic language skills, respectively. Results are interpreted to demonstrate a mediating effect of language on the WM component of EF when assessed directly or indirectly. Implications for theories linking language skill to EF in the ASD population are discussed, and the observed deficit is compared with findings on EF and language ability in the SLI population.