2026
Biological sex and bilingualism: Its impact on risk and resilience for dementia
Auteurs:
Calvo, N., Phillips, N., Bialystok, E., Einstein., G.
Revue:
Alzheimer's & Dementia
Abstract
Introduction: The relationship between biological sex, considered a risk factor for Alzheimer’s disease (AD), and bilingualism, a resilience factor, is unclear. We assessed this relationship in 335 individuals with mild cognitive impairment (MCI) in a Canadian cohort.
Methods: We used univariate analysis and structural equation modelling to study the relationship between female sex and bilingualism. We created a resilience index (RI) for each participant using the residual approach. Logistic and linear regressions predicted cognitive and brain health in relation to RI.
Results: Overall, bilingual males had increased RI. Higher RI was associated with less risk of AD and less neuropathology and glial activation as indexed by plasma p-tau181, neurofilament light, and glial fibrillary acidic protein.
Discussion: In MCI, the combination of elevated estradiol levels due to aromatization and bilingualism may provide synergistic protection for verbal memory, making old bilingual males more resilient.
Plain Language Summary
The question we studied: How does speaking two languages (bilingualism) affect the brain differently in women and men when it comes to signs of Alzheimer’s disease (pathology) and how well their brains can stay strong and flexible as they get older (cognitive resilience)?
How we studied it: We used a large and well-characterized database of Canadian participants, the Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) of the Canadian Consortium on Neurodegeneration and Aging (CCNA).
What we found: Overall, there was a relationship among sex hormones (estradiol, testosterone), bilingualism and verbal memory which influenced cognitive resilience. Bilingual males had increased cognitive resilience, followed by bilingual females, monolingual (speakers of only one language) males and monolingual females. Higher cognitive resilience was associated with less risk of developing AD but also with fewer signs of AD in the brain.
Why it matters: These findings show the importance of speaking a second language on cognitive resilience and on the prevention of dementia. They also show that the effect of bilingualism is less for women than for men. It is important to understand what can be a protective factor for the brain, speaking more than one language, and why the effect differs in men and woman for better interventions.
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