Executive function in Down syndrome: A meta-analysis.

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.