Impact of Bilingualism on the Cognitive Outcomes in Stroke Survivors: A Systematic Review
Ece Eldem1, Shubham Misra1, Terence Quinn2, Lucas Driskell1, Alice Perez1, Carmen Carrion1, Todd Constable1, Joseph Schindler1, Yize Zhao1, Jason Sico1, Jason D Hinman3, Heather Allore1, Swathi Kiran4, Jubin Abutalebi5, Jean-Marie Annoni6, Nishant K. Mishra1
1Yale University, 2University of Glasgow, 3University of California Los Angeles, 4Boston University, 5University Vita-Salute San Raffaele, 6Universite de Fribourg
Objective:
To examine existing evidence on the effect of bilingualism on cognitive outcomes in the stroke population.
Background:
Stroke is associated with an increased risk of vascular cognitive impairment. Bilingualism promotes cognitive reserve and resilience through the effect of language switching on the cognitive control systems and is suggested to delay cognitive impairment and dementia in non-stroke populations. However, the impact of bilingualism on cognitive outcomes in stroke patients has not been thoroughly examined.
Design/Methods:
We systematically reviewed published literature in medical databases that compared the cognitive assessment scores between mono- and bilingual stroke patients using cognitive assessment tool(s). We planned (1) a meta-analysis of outcome data using the subdomains of cognitive assessment tool(s); (2) a qualitative comparison if a meta-analysis was impossible. We assessed the study quality using the Joanna Briggs Institute tool.
Results:
Our literature search yielded 348 articles, and six were eligible for our systematic review (N=528 bilinguals; 737 monolinguals). One study was of good quality (Hope, 2015), and five were of moderate quality. We could not perform a meta-analysis because of disparate cohort characteristics and study methods, choice of cognitive tests, outcome measures, and lack of common data elements. Studies used one cognition and three language assessment batteries as cognitive assessment tools. In two studies, bilinguals performed better than monolinguals on cognitive tests (Paplikar, 2019; Alladi, 2016). On language assessment batteries, bilinguals performed better than monolinguals in four studies (Paplikar, 2019; Lahiri, 2020; Ardila, 2021; deLetter, 2021) and poorly in one study (Hope et al., 2015). ACE-R was significantly greater in bilinguals than monolinguals (Paplikar, 2019; Alladi, 2016).
Conclusions:
The current literature on the relationship between bilingualism and cognitive outcomes in stroke patients is sparse and insufficient. Harmonization of study methods (e.g., cognitive assessment tools) and common-data elements are critically needed to advance bilingualism research.