Characteristic Executive Dysfunction for High-Functioning Autism Sustained to Adulthood

Abstract

The comprehensiveness and severity of executive dysfunction in high-functioning autism (HFA) spectrum disorder have not reached a unified conclusion especially in patients in adulthood. Clarifying this issue is critical for guiding clinical diagnosis and targeted intervention. The primary objective of the present meta-analysis was to study the characteristics of executive function (EF) in adults with HFA compared to typically developing (TD) adults, by taking five key components into consideration, including inhibition, working memory, flexibility, planning, and fluency. The PubMed and Embase databases were searched to identify peer-reviewed studies that compared EF in adults with and without HFA from 1980 to November 2018. Hedges' g effect sizes were computed to measure the primary outcome. Moderators like age, sex, and diagnostic tools were controlled using meta-regressions. Forty-two studies satisfying the selection criteria were included, which resulted in a large sample size of 2419 participants. A moderate overall effect size for reduced EF across domains was found in adults with HFA, compared with TD (g = 0.57, 95% confidence interval 0.47-0.66). Subsequently, a broad executive dysfunction was found in adults with HFA in this study (flexibility [g = 0.69], planning [g = 0.64], inhibition [g = 0.61], working memory [g = 0.48], fluency [g = 0.42]), with the predominated impairment on flexibility and planning. Taken together, these results provide evidence for the executive dysfunction hypothesis and may assist in the clinical diagnosis and targeted intervention, suggesting the necessity of sustained intervention on EF for individuals with HFA from childhood to adulthood. LAY SUMMARY: The meta-analysis explored the characteristics of EF in adults with high-functioning autism (HFA) comparing to typically developing controls. Moderate effect sizes for reduced EF across domains were found in adults with HFA, with the flexibility and planning being the most predominately impaired. A comprehensive measurement of EF in adults with HFA has important clinical implications for the diagnosis, treatment, prognosis, and a fundamental understanding for developmental trajectory of these patients.

Keywords: Asperger's syndrome; executive function; high-functioning autism spectrum disorder; meta-analysis.