STUDY FINDS
MONTREAL — Learning a second language offers benefits beyond ordering food on vacation or reading foreign literature. Recent research from Concordia University suggests bilingualism might actually help protect the brain against some devastating effects of Alzheimer’s disease.
Scientists have long observed that some people maintain their thinking abilities despite significant brain damage. This disconnect, where brain deterioration doesn’t necessarily cause expected cognitive problems, has prompted researchers to develop ideas like “brain reserve,” “cognitive reserve,” and “brain maintenance” to explain this resilience. This study, published in Bilingualism: Language and Cognition, found evidence that speaking two or more languages might boost this resilience, especially through brain maintenance in people with Alzheimer’s.
Alzheimer’s accounts for about two-thirds of dementia cases worldwide and typically progresses from subjective cognitive decline (SCD) to mild cognitive impairment (MCI) before developing into full Alzheimer’s. This progression usually comes with brain shrinkage, particularly in the medial temporal lobe, which includes the hippocampus, a structure essential for forming new memories.
Earlier studies suggested bilingual individuals might experience a 4-to-5-year delay in Alzheimer’s symptom onset compared to those who speak just one language. But how exactly bilingualism might shield against cognitive decline hasn’t been fully understood. This new research examines the structural brain differences between bilinguals and monolinguals (people who only speak one language) across various stages of Alzheimer’s progression.
The research team analyzed data from 364 participants from two major Canadian studies. Participants ranged from cognitively healthy individuals to those with subjective cognitive decline, mild cognitive impairment, and Alzheimer’s disease.
Using brain imaging, researchers measured the thickness and volume of specific brain regions involved in language processing and areas typically affected by Alzheimer’s. They wanted to see if bilinguals showed signs of greater “brain reserve” (more neural tissue in language-related regions) or “cognitive reserve” (maintaining cognitive function despite significant brain deterioration).
Unlike some previous studies, bilinguals didn’t show greater brain reserve in language-related regions compared to monolinguals. However, a difference emerged when looking at the hippocampus, one of the first areas damaged by Alzheimer’s.
Older monolinguals with Alzheimer’s showed substantial reduction in hippocampal volume compared to those with milder impairment, following the expected pattern of brain degeneration. But bilinguals with Alzheimer’s showed a different pattern: their hippocampal volumes weren’t significantly smaller than bilinguals with milder cognitive issues.