Use of Multiple Languages Provides Cognitive Reserve Amidst Age-Related White Matter Changes

Bilingualism can stimulate brain plasticity and is often associated with better executive function. We investigated whether language usage was related to the volume of white matter lesions in a cohort of middle-aged to older adults with different multilingual characteristics, including monolingualism in daily life (use of one language), bilingualism (use of two languages), and multilingualism (active use of 3 languages, i.e., Catalan, Spanish, English). We also explored cognitive status and cognitive change over a 2-year follow-up period linked to possible associations between language usage and white matter status to provide insights into the theory of cognitive reserve (CR).

All participants (N = 397, age range: 45-69, 50.1% female) underwent cognitive and structural magnetic resonance imaging assessments at baseline, and 306 of them completed additional cognitive and neuroimaging assessments 2 years later. Active use of languages was computed at baseline with the Shannon Entropy equation, which measured the frequency of use of each language in 4 different contexts: home, work, friends, and family. The volume of white matter hypointensities (WM-hypo) was determined using FreeSurfer.

There was a positive correlation between Entropy values and WM-hypo. Compared to monolinguals, participants using 3 languages daily presented equivalent cognitive function and increased white matter lesions, both at baseline and follow-up examinations.

Among middle-aged participants with equivalent cognitive levels, active multilingualism was associated with greater white matter deterioration, suggesting increased CR.