Working memory multicomponent model outcomes in individuals with traumatic brain injury: Critical review and meta-analysis

Objective: Traumatic Brain Injury (TBI) often leads to cognitive impairments, particularly regarding working memory (WM). This meta-analysis aims to examine the impact of TBI on WM, taking into account moderating factors which has received little attention in previous research, such as severity of injury, the different domains of Baddeley's multi-component model, and the interaction between these two factors, as well as the interaction with other domains of executive functions. Method: Following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic review and meta-analysis searched Google Scholar, PubMed, and PsycNET for studies with objective WM measures. Multiple meta-analyses were performed to compare the effects of TBI severity on different WM components. Twenty-four English, peer-reviewed articles, mostly cross-sectional were included. Results: TBI significantly impairs general WM and all Baddeley's model components, most notably the Central Executive (d' = 0.74). Severity categories, mild-moderate and moderate-severe, were identified. Impairment was found across severities, with "moderate-severe"demonstrating the largest effect size (d' = 0.81). Individuals with moderate-severe TBI showed greater impairments in the Central Executive and Episodic Buffer compared to those with mild-moderate injury, whereas no such differences were found for the Phonological Loop and Visuospatial Sketchpad. Conclusions: These findings enhance our understanding of WM deficits in varying severities of TBI, highlighting the importance of assessing and treating WM in clinical practice and intervention planning.