A Meta-Analysis of Working Memory in Individuals with Autism Spectrum Disorders

Background: Autism spectrum disorders (ASD) are lifelong neurodevelopmental disorders. Numerous studies have shown that individuals with Autism spectrum disorder (ASD) are associated with working memory (WM) deficits, however, the findings from research on WM impairments in ASD has been inconsistent and it is not clear whether WM deficits are commonly experienced by individuals with ASD.

Objectives: To determine whether individuals with ASD experience significant impairments in WM and whether there are specific domains of working memory that are impaired.

Methods: We conducted a comprehensive systematic review and a meta-analysis using four electronic databases EMBASE (OVID), MEDLINE (OVID), PsychINFO (EBSCOHOST), and Web of Science, to examine the literature to investigate whether people with ASD experience impairments related to WM. Meta-analyses were conducted separately for phonological and visuospatial domains of WM. Subgroup analyses investigated age and intelligence quotient as potential moderators.

Results: A total of 29 papers containing 34 studies measuring phonological and visuospatial domains of WM met the inclusion criteria. WM scores were significantly lower for individuals with ASD compared to typically developed (TD) controls, in both the visuospatial domain when investigating accuracy (d: -0.73, 95% CI -1.04 to -0.42, p < 0.05) and error rates (d: 0.56, 95% CI 0.25 to 0.88, p<0.05), and the phonological domain when investigating accuracy (d:-0.67, 95% CI -1.10 to -0.24, p>0.05) and error rate (d: 1.45, 95% CI -0.07 to 2.96, p=0.06). Age and IQ did not explain the differences in WM in ASD.

Conclusions: The findings of this meta-analysis indicate that across the lifespan, people with ASD demonstrate large impairments in WM across both phonological and visuospatial WM domains when compared to people without ASD.