Executive function in Down syndrome: A meta-analysis

Abstract

Background: Executive function (EF) refers to a set of cognitive processes involved in goal-oriented behavior-especially inhibition, attention shifting, and working memory. EF has been identified as a probable area of difficulty in Down syndrome (DS), but the exact nature of the difficulty has not been well-established.

Aims: The meta-analysis sought to confirm or disconfirm EF as an area of difficulty in DS and elucidate an EF profile.

Methods and procedures: A random-effects meta-analysis was conducted on 57 studies that compared a group with DS to a typically developing (TD) mental age matched group on one or more executive function tasks. Heterogeneity was examined and moderators analyzed.

Outcomes and results: The overall mean weighted effect size was large (d = -0.87), indicating poorer EF in groups with DS vs TD groups. Heterogeneity was significant, and moderator analysis revealed an EF profile with a very large effect for verbal WM/STM, a large effect for shifting, and moderate effects for inhibition and nonverbal WM/STM. Skewness analysis suggested that mean effect sizes might have been dampened, especially for WM/STM and shifting.

Conclusions and implications: Individuals with DS display a pronounced difficulty in EFs; implications for interventions and future research are discussed.

Keywords: Developmental disability; Down syndrome; Executive function; Inhibition; Intellectual disability; Shifting; Short-term memory; Working memory.