The Association Between Multilingualism and Executive Function in the Canadian Longitudinal Study on Aging: Results from the Baseline Comprehensive Cohort

Abstract

Background: Identifying factors that protect against cognitive impairment is key to healthy aging. Cognitive stimulation through multilingualism may be protective against cognitive impairment, such as low executive function. Evidence of a multilingual advantage on executive function tasks is mixed, and very few studies have examined the role of language similarity on cognition. Objectives: To examine the association of: 1) the number and 2) the similarity of spoken languages with executive function in Canadians aged 45–85 years.

Methods: Baseline cross-sectional data from the Canadian Longitudinal Study on Aging’s Comprehensive cohort were used for analyses of the number (n=22,249) and similarity (n=20,440) of languages. Language similarity was examined in bilinguals, where similar bilingualism referred to individuals whose two spoken languages were within the same Indo-European language family subgroup. Low executive function was derived from five executive function tests, where raw scores were converted to z-scores, summed, and then dichotomized based on a cut-point of ≥1.5 SD below the mean of the overall score in a weighted cognitively healthy subsample. Weighted multivariable logistic regression models were adjusted for sociodemographic, general health, health behaviours/lifestyle, and cognitively stimulating covariates. The fully adjusted model was stratified by participation in cognitive leisure activities.

Results: The number of languages spoken was significantly associated with executive function in a dose-response manner: compared to those who spoke one language, individuals who spoke up to, and including, four languages had lower odds of low executive function. The association between language similarity and low executive function was not significant. When stratified by cognitive leisure activities, the same conclusions held in those who participated in these cognitive activities infrequently, but not every day or several time a week.

Conclusion: The number of languages spoken is protective against low executive function, with peak protection occurring at four languages, but the similarity of spoken languages does not provide any protective effect. Therefore, an individuals may benefit from learning any additional Indo-European language. Moreover, protection against low executive function can be achieved through different combinations of cognitively stimulating activities, but language learning would be particularly beneficial for persons who engage infrequently in traditional cognitive activities.