Discourse and Cognition in Speakers with Acquired Brain Injury (ABI): A Systematic Review

Background: Cognitive impairment, particularly of executive functioning, has been implicated in deficits in spoken discourse production following acquired brain injury (ABI). However, due to variation in the methodologies and heterogeneity of findings across studies, the nature and extent of this association is not well understood. Aims: This review aims to synthesize the literature investigating associations between cognitive deficits and discourse impairment after ABI. It is reported in accordance with guidelines of The Preferred Reporting Items of Systematic Reviews and Meta-Analyses. Data sources: Searches were conducted of a variety of databases including Medline, PsycINFO, EMBASE, CINAHL, ProQuest, Cochrane and ERIC. Additional studies were identified via reference harvesting. Eligibility criteria: Studies were included if they reported data on participants with ABI, assessed spoken discourse production and cognitive function, and performed statistical analyses to determine the association between discourse and cognitive variables. This review excluded non-English sources and those not published in peer-reviewed journals. Meta-analyses were not conducted due to variability across tools and terminology used to describe participant injury- and non-injury-related characteristics and outcomes. Results: Twenty-five observational studies were included in the review. Findings revealed significant associations between multiple cognitive functions and discourse across micro-linguistic to super-structural measures. Methodological and terminological inconsistencies were identified across studies, which limited systematic comparison of the results. Conclusions: This review revealed present, yet heterogeneous, relationships between cognitive and discourse deficits in speakers with ABI. Associations were interpreted in light of a well-established model of discourse processing. Greater comparison across studies would have been facilitated by a standard nomenclature in relation to cognitive constructs and standardized discourse assessment. Future research should explore the influence of injury- and participant-related factors on discourse-cognitive relationships. The lack of information on conversational discourse and paediatric ABI limits the generalizability of this review to daily interaction following ABI. While applicable across the lifespan, in-depth investigation of discourse following ABI in childhood and adolescence is a priority due to complex changes in language and cognition, and the potential for impairments profoundly impact social, emotional and academic progression into adulthood. Given the centrality of remediating cognitive-communication difficulties in ABI, the interrelationships between discourse and cognition should retain a critical focus of research. This will inform clinical management and future research with this population. Findings have implications for our theoretical understanding of discourse and the nature of its breakdown in ABI.