Summary: Research indicates bilingualism can delay the clinical onset of Alzheimer’s disease by up to five years. A recent neuroimaging study finds that, among older adults with Alzheimer’s, those who are bilingual tend to have larger hippocampi—a critical brain structure for memory—than comparable monolinguals. These findings point to a form of brain resilience associated with bilingual experience that helps preserve memory-related brain tissue even in the presence of Alzheimer’s pathology.
Bilingualism may contribute to overall brain health during aging. While this study did not find evidence of enhanced brain reserve in language-specific cortical regions, the preservation of the hippocampus suggests bilingual experience supports brain maintenance in areas crucial for learning and memory.
Key Facts:
- Bilingualism has been associated with a delay of up to five years in the clinical onset of Alzheimer’s symptoms.
- Among older adults with Alzheimer’s disease, bilingual participants showed larger hippocampal volume than matched monolingual participants.
- The results suggest bilingualism supports brain maintenance—preserving structure and function—rather than broad language-area brain reserve.
Source: Concordia University
Bilingualism and cognitive aging
Bilingualism has been linked to cognitive benefits throughout life and into older adulthood. Several studies suggest that lifelong engagement with more than one language can contribute to cognitive and social engagement, both of which are associated with healthier aging trajectories. One notable observation across prior research is a delay in the clinical onset of Alzheimer’s disease among people who regularly use two or more languages compared with monolingual individuals.
In a new article in the journal Bilingualism: Language and Cognition, researchers at Concordia University examined how bilingualism relates to structural brain features relevant to aging and Alzheimer’s disease. Using neuroimaging and surface-based morphometry, the team measured cortical thickness and regional volumes in brain areas linked to language processing and Alzheimer’s-related degeneration.
The study compared monolingual and bilingual older adults across a continuum of cognitive status: cognitively normal individuals, people showing early subjective cognitive decline or mild cognitive impairment, and individuals diagnosed with Alzheimer’s disease. When participants were matched for age, education, overall cognitive performance and memory, the bilingual group with Alzheimer’s displayed larger hippocampal volume than the monolingual group.
“There was greater brain matter in the hippocampus, which is the main region in the brain for learning and memory and is highly affected by Alzheimer’s,” says the study’s lead author, PhD candidate Kristina Coulter. The study was co-authored by Natalie Phillips, Professor in the Department of Psychology and Concordia University Research Chair in Sensory-Cognitive Health in Aging and Dementia.
Localized resilience
The research frames its findings in terms of brain resilience, which encompasses three related concepts:
- Brain maintenance: the preservation of brain structure and function as a person ages, potentially supported by lifestyle factors and ongoing mental activity;
- Brain reserve: the physical capacity of the brain—extra volume or neuronal resources—that can help maintain function despite damage or pathology;
- Cognitive reserve: the ability to recruit alternate neural networks or strategies to achieve cognitive tasks when the usual circuits are compromised.
This study did not find evidence that bilingualism produced larger language-region structures (brain reserve) nor did it demonstrate greater cognitive reserve specifically in Alzheimer’s-related regions. Instead, the principal result points to brain maintenance of the hippocampus in bilingual individuals: hippocampal volume remained comparable across cognitively normal participants, at-risk groups and those with Alzheimer’s within the bilingual sample, while monolingual participants showed reduced hippocampal volume with disease progression.
“Speaking more than one language is one of several ways to be cognitively and socially engaged, which promotes brain health,” explains Natalie Phillips. The study’s design allowed researchers to explore how bilingualism might influence brain structure across different stages of dementia risk, from healthy aging to diagnosed Alzheimer’s disease.
Future research from this team will investigate whether multilingualism—knowledge and use of more than two languages—has a comparable or stronger influence on brain networks and resilience. For this analysis, the researchers used data from the Comprehensive Assessment of Neurodegeneration and Dementia Study (COMPASS-ND) and the Consortium for the Early Identification of Alzheimer’s disease–Quebec (CIMA-Q).
About this bilingualism and Alzheimer’s disease research news
Author: Patrick Lejtenyi
Source: Concordia University
Contact: Patrick Lejtenyi – Concordia University
Image credit: Neuroscience News
Original Research: Open access. “Bilinguals show evidence of brain maintenance in Alzheimer’s disease” by Kristina Coulter et al., published in Bilingualism: Language and Cognition.
Abstract
Bilinguals show evidence of brain maintenance in Alzheimer’s disease
The researchers examined brain and cognitive reserve associated with bilingualism in older adults with, or at-risk for, Alzheimer’s disease using data from the Canadian Consortium on Neurodegeneration in Aging and the Quebec Consortium for the Early Identification of Alzheimer’s Disease. Surface-based morphometry measured cortical thickness and volume of language-related and Alzheimer’s-related brain regions. The study found no evidence of brain reserve in language-related cortical regions. However, reduced hippocampal volume was observed for monolingual, but not bilingual, older adults with Alzheimer’s. These findings suggest bilingualism may contribute to reserve in the form of brain maintenance in the context of Alzheimer’s disease.