Knowing two languages could preserve your brain for longer, even with Alzheimer’s. (stoatphoto/Shutterstock)
In a nutshell
- Bilinguals with Alzheimer’s showed larger hippocampal volumes, a brain region critical for memory, compared to monolinguals at the same stage of the disease, suggesting a potential structural benefit of speaking multiple languages.
- No evidence was found for brain or cognitive reserve, but researchers observed signs of brain maintenance in bilinguals, meaning their brain structure appeared better preserved despite Alzheimer’s progression.
- Even late bilinguals with moderate language ability showed this effect, hinting that the brain benefits of bilingualism might extend beyond childhood fluency or daily use, and could be relevant to public health strategies for aging populations.
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.
While monolingual brains showed progressive shrinkage as the disease worsened, bilingual brains seemed to maintain their hippocampal volume despite disease progression. This points to what researchers call “brain maintenance,” preserving brain structure over time despite aging or disease.
The hippocampus is vital for forming new memories, and its deterioration closely connects with the memory loss so characteristic of Alzheimer’s. If bilingualism helps preserve hippocampal volume, it could explain why some studies have found delayed symptom onset in bilingual Alzheimer’s patients.
The bilingual participants came from diverse backgrounds, with about 38% reporting English as their first language, 39% reporting French, and the rest reporting various other languages. About 68% knew two languages, 22% knew three, and some participants reported knowing up to seven languages. Interestingly, many bilingual participants could be described as “late bilinguals,” those who learned their second language after age 5, with moderate self-reported second language ability.
The potential brain benefits of bilingualism might not be limited to those who grew up speaking multiple languages or who are highly fluent in their second language. Even learning a second language later in life and achieving moderate skill might contribute to cognitive resilience.
What does this mean for ordinary people? While the study doesn’t suggest that learning a second language will prevent Alzheimer’s, it adds to growing evidence that certain lifestyle factors, including language learning, may help build resilience against cognitive decline.
The benefits of learning a second language extend far beyond communication skills. The mental demands of managing multiple languages may help build a more resilient brain, one better equipped to withstand the challenges of aging and disease. While learning a second language is no cure, it could help maintain thinking abilities for longer despite underlying brain damage.
Paper Summary
Methodology
The researchers used advanced brain imaging to examine participants’ brain structures. They employed surface-based morphometry methods through software called FreeSurfer to measure the thickness and volume of specific brain regions. This method differs from previous studies, offering more detailed brain structure assessment. The team reconstructed and measured brain volumes on 3T MRI scans following a standardized Canadian protocol. They looked at language-related regions (parts of the brain involved in language processing) and Alzheimer’s-related regions (including the hippocampus and related structures). To ensure accurate results, they matched participants within each diagnosis group on age, sex, education, memory performance, and cognitive function. The analysis used statistical models to examine how diagnosis and language background affected brain structure, while accounting for factors like age and head size.
Results
The study found that older adults who spoke only one language showed the expected pattern of hippocampal shrinkage across Alzheimer’s progression, with significant volume loss in those with Alzheimer’s compared to earlier stages. However, bilingual older adults maintained their hippocampal volume even with Alzheimer’s. Specifically, bilinguals with Alzheimer’s had noticeably larger volumes in several hippocampal regions compared to monolinguals with Alzheimer’s. This pattern suggests bilingualism may help preserve brain structure despite disease progression. Interestingly, researchers didn’t find evidence of greater brain reserve in language-related regions for bilinguals, contrary to some earlier research. They also didn’t find evidence of cognitive reserve in the traditional sense. Instead, the results point specifically to preservation of hippocampal volume in bilinguals with Alzheimer’s.
Limitations
Several limitations should be kept in mind when interpreting these findings. The study captured brain differences at one point in time rather than tracking changes over time, limiting direct observation of brain maintenance, which is inherently a process that unfolds over time. The researchers used a simple measure of bilingualism—participants reported the number of languages they knew without detailed assessment of fluency or usage patterns for everyone. The sample consisted of highly educated older adults (about 15 years of education on average), which may not apply to populations with different educational backgrounds. The gender balance varied across groups, with more women in the cognitively unimpaired and subjective cognitive decline groups, and more men in the Alzheimer’s groups. While immigration status was considered, it wasn’t found to significantly predict brain differences in any region examined, though about 11% of monolinguals and 32% of bilinguals were immigrants.
Discussion and Takeaways
The researchers interpret their findings as evidence that bilingualism helps maintain brain structure in Alzheimer’s, particularly preserving hippocampal volume. This maintenance might explain why some studies have found delayed symptom onset in bilingual Alzheimer’s patients. Notably, the researchers didn’t find evidence of greater brain reserve in language-related regions or cognitive reserve in Alzheimer’s-related regions for bilinguals. They suggest that the variety of bilingual experience in their sample—including many late second language learners with moderate proficiency who didn’t use their second language daily—might explain the lack of brain and cognitive reserve effects. The authors note that many bilinguals in their sample learned their second language later in life and didn’t use it daily, which may have limited the emergence of cognitive or brain reserve effects. The researchers emphasize that studies tracking individuals over time are needed to further explore how bilingualism relates to maintained brain structure in Alzheimer’s, and how this might connect to cognitive changes over time.
Funding and Disclosures
The research received partial support from a grant awarded to Dr. Natalie Phillips from the Natural Sciences and Engineering Research Council Discovery Grant Program. Dr. Phillips is part of Team 17 in the Canadian Consortium on Neurodegeneration in Aging (CCNA), which receives funding from the Canadian Institutes of Health Research and other partners. Some data came from the Québec Consortium for the Early Identification of Alzheimer’s disease (CIMA-Q), supported by several organizations including the Fonds de recherche du Québec–Santé (FRQS) – Pfizer Innovation Program and others. The researchers declared no competing interests.
Publication Information
The study “Bilinguals show evidence of brain maintenance in Alzheimer’s disease” was authored by Kristina Coulter, Natalie A. Phillips, and research groups from CIMA-Q and COMPASS-ND. It appeared in Bilingualism: Language and Cognition (Volume 27, pages 1029-1038) published by Cambridge University Press. The paper was received in June 2023, revised in February 2024, accepted in February 2024, and published online in September 2024. It’s available as an Open Access article under the Creative Commons Attribution-NonCommercial-NoDerivatives license.
