Exploring Brain Health in Aging
What makes some older adults maintain sharp memories and healthy brains as they age? Recent research delved into the interplay of social, linguistic, and hormonal factors that might impact cognitive health.
With the aging population in Canada on the rise—about one in eight Canadians is now over 70 and 1.7 million are 80 or older—understanding brain health has become increasingly important. These shifts point to a larger group of older individuals who may face cognitive decline, which emphasizes the need to look into potential protective factors.
Previous studies suggest that being bilingual could be a protective factor. Interestingly, the 2021 census revealed a rise in bilingualism, with about 41 percent of Canadians conversing in more than one language.
While bilingualism might contribute to cognitive resilience, it’s likely not the only factor at play. For instance, verbal memory—the capacity to retain words—has been associated with cognitive resilience, too.
Hormones like estrogen and testosterone, present in both genders, may also play a role in how the brain ages. However, the interaction between these three elements—bilingualism, verbal memory, and sex hormones—has not been thoroughly examined until now.
In our recent study conducted in Canada, we designed a research project to address this gap. We discovered that bilingualism appears to interact with verbal memory and sex hormones, influencing dementia risk in surprising ways.
We analyzed data from 335 older adults with mild cognitive impairment and 170 individuals with Alzheimer’s disease, sourced from the Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) cohort, which includes over 1,200 Canadians aged 50 to 90.
Utilizing this robust database, we explored how these factors collectively affect cognitive resilience, brain structure, and blood biomarkers linked to Alzheimer’s disease.
A resilience index was crafted for each participant, taking into account sex hormones, verbal memory, bilingual fluency, education, age, and immigration status. Age, education, and immigration were considered potential influences on cognitive resilience for various reasons, such as differences in language exposure and educational opportunities.
A rise in resilience index scores showed a significant reduction in the likelihood of dementia-related issues. Higher scores also correlated with improved performance on cognitive tests like the Montreal Cognitive Assessment (MoCA) and fewer markers of neurodegeneration.
Interestingly, bilingual participants exhibited the best resilience index scores, but the effects differed depending on biological sex, highlighting complex dynamics at play.
This study challenges the notion that resilience or risk can be understood separately from either biological or social factors. By investigating the interaction between bilingualism and hormonal influences, we can see how they together shape cognitive resilience.
Another notable finding was related to verbal memory performance, which aligned with previous research showing that women tend to excel in this area. This observation is clinically relevant, given that verbal memory often serves as an indicator of overall cognitive function, affecting dementia diagnoses in women.
One might think that bilingual women would have the upper hand, benefiting from both bilingualism and strong verbal memory. Contrary to expectations, bilingual men displayed greater cognitive protection.
Our findings imply that the combination of certain factors might enhance verbal memory and cognitive resilience, particularly in aging men—specifically, the conversion of testosterone to estradiol (aromatization) alongside bilingual experience. For men with mild cognitive impairment, elevated estradiol levels alongside bilingualism appear to create a protective effect on verbal memory.
In summary, this research suggests that bilingual men might be more resilient to cognitive decline, while sex hormones could significantly impact the dementia risk in older women.
These insights highlight the necessity for further exploration into how sex hormones affect brain health, as well as the need for more accurate measures beyond verbal memory for diagnosing cognitive decline in Canada.
