Executive function in probands with autism with average IQ and their unaffected first-degree relatives

Objective: This study aimed to characterize executive function (EF) in pedigrees of children with autism spectrum disorder (ASD) and average IQ. The authors examined the hypothesis that deficits in EF relate to lower levels of adaptive functioning, and they assessed evidence for a cognitive extended phenotype in unaffected relatives in a large, well-characterized sample.

Method: Proband EF was assessed by parent-report questionnaires (Behavior Rating Inventory of Executive Functioning [BRIEF], n = 109) and child neuropsychological tests (Delis-Kaplan Executive Functioning System [D-KEFS], n = 35). EF also was examined in parents (D-KEFS, n = 335) and unaffected siblings (BRIEF, n = 114; D-KEFS, n = 57). Adaptive functioning was assessed by the Vineland Adaptive Behavior Scales-II (n = 155). All data were obtained from the Autism Consortium Clinical Genetics Database.

Results: Individuals with ASD showed important EF weaknesses. Multiple regression analyses showed that parent-reported EF deficits were related to profound decreases in adaptive functioning even after controlling for age, IQ, and severity of ASD symptoms. Parent-reported EF also was related to adaptive skills in preschoolers. First-degree unaffected relatives did not demonstrate difficulties with EF compared with normative data.

Conclusion: In this study, EF impairments do not appear to relate to broad familial risk factors for ASD but may be associated with factors relevant to the expression of ASD in probands. Results support the benefits of EF assessment as a way to identify potential therapeutic targets that could lead to improved adaptive behavior in children with ASD and average IQ.