Scientists Explore Why Dementia Risk May Differ Between Bilingual Men And Women

Many older adults maintain sharp thinking skills despite age-related changes in the brain. New research suggests that speaking more than one language, combined with specific hormone patterns, may help explain this resilience in ways scientists did not expect.

A team of researchers in Canada examined how social, linguistic, and biological factors work together to influence brain health. Their study, published in the journal Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, focused on bilingualism, verbal memory, and sex hormones.

Canada's aging population makes this question urgent. The 2021 census shows that one in eight Canadians is 70 or older, and 1.7 million people are at least 80, raising the number at risk of cognitive decline and dementia. At the same time, 41 percent of Canadians now speak more than one language.

How the Canadian study worked

The researchers used data from the Comprehensive Assessment of Neurodegeneration and Dementia, known as COMPASS-ND. This national cohort, part of the Canadian Consortium on Neurodegeneration and Aging, includes more than 1 200 adults aged 50 to 90 recruited at over 30 sites.

For this analysis, the team studied 335 older adults with mild cognitive impairment and 170 patients diagnosed with Alzheimer's disease. They examined cognitive test scores, brain imaging, blood-based markers of Alzheimer's, and detailed information about language use and hormone levels.

They built a resilience index for each participant that combined verbal memory performance, bilingual proficiency, levels of sex hormones such as estrogen and testosterone, education, age, and immigration status. These additional factors help capture lifetime social and educational experiences.

Resilience index and dementia markers

Each step up on this resilience index was linked with lower odds of dementia-related brain changes. Participants with higher scores performed better on clinical tools such as the Montreal Cognitive Assessment, a widely used screening test for cognitive impairment.

Higher resilience scores were also associated with lower levels of biological markers tied to neurodegeneration and glial activation. Glial activation reflects a state in which the brain's support cells become reactive in response to disease or injury, and it is often observed in Alzheimer's pathology.

On average, bilingual participants had the highest resilience index values. However, the pattern differed by biological sex, revealing a complex interaction between language experience and hormone biology that challenges earlier, more simplistic views of dementia risk.

Why men and women differ

The study confirmed a well-known finding: women tend to outperform men on verbal memory tasks. Because these tests are often used as a proxy for overall cognitive function, this difference can affect how dementia is diagnosed, and sometimes may delay detection in women.

Given past studies suggesting that bilingualism protects against cognitive decline, the team expected bilingual women, with both verbal memory strengths and multilingual experience, to be especially resilient. Instead, older bilingual men showed greater signs of protection at the brain level.

The researchers propose that in men with mild cognitive impairment, a process called aromatization may be key. Aromatization converts testosterone into estradiol, a form of estrogen, and higher estradiol levels in this group appeared to combine with bilingualism to better preserve verbal memory and reduce neurodegenerative changes.

Implications for dementia diagnosis

The findings suggest that bilingual men may have higher resilience to Alzheimer's-related pathology than previously assumed, while hormone patterns could leave some aging women more vulnerable than their cognitive test scores alone might indicate. This complicates standard approaches to risk assessment.

Because verbal memory tests often favor women, clinicians may underestimate early decline in female patients if they rely too heavily on these tools. The authors argue that diagnostic strategies should incorporate a broader set of cognitive measures and consider sex-specific and hormonal influences.

The study also highlights that social and biological factors cannot be evaluated in isolation. Bilingualism, education, hormone levels, and life experience appear to intersect to shape how the aging brain copes with disease, underscoring the need for more personalized approaches to dementia prevention.

Researchers say future work should track hormone changes across the lifespan, explore the impact of hormone therapies, and examine how different types and intensities of bilingual experience affect brain health. As populations age and multilingualism grows, these questions will become increasingly important for public health planning.