Bilingual experience affects white matter integrity across the lifespan

Area of Science:

• Neuroscience
• Cognitive Science
• Aging Research

Background:

• Bilingualism is linked to cognitive reserve, potentially delaying dementia onset.
• Research on bilingualism's effects on aging cognition often overlooks middle-aged adults and treats bilingualism dichotomously.
• The impact of bilingualism's heterogeneity on age-related white matter decline is understudied.

Purpose of the Study:

• To investigate how bilingualism and the degree of bilingual engagement affect age-related white matter integrity decline.
• To examine the trajectory of white matter integrity across the lifespan in monolinguals versus bilinguals.
• To determine if lifelong bilingual engagement influences the rate of white matter aging.

Main Methods:

• Diffusion Tensor Imaging (DTI) was used to assess white matter integrity.
• Language history data were collected from monolingual and bilingual participants across a wide age range.
• Statistical analyses included generalized additive models and general linear models.

Main Results:

• Monolinguals showed a significant age-related decline in white matter integrity (fractional anisotropy in the right superior longitudinal fasciculus).
• Bilinguals did not exhibit a significant age effect in the same white matter region, suggesting preserved integrity.
• Greater lifelong engagement in bilingualism correlated with a slower decline in white matter integrity with age.

Conclusions:

• Bilingualism, particularly the degree of engagement, modulates the trajectory of age-related white matter decline.
• Lifelong bilingual experience may offer a protective effect on white matter integrity across the lifespan.
• Findings highlight the importance of considering the heterogeneity of bilingualism in aging research.