While the path to dementia can vary, certain common risk factors heighten the likelihood of diagnosis. Nevertheless, a significant new study reveals that the impact of these factors differs among older adults. The findings are detailed in the journal Biology of Sex Differences.
Some risk factors seem to affect women’s cognitive function more profoundly than men’s, and the accumulation of multiple risk factors over a lifetime appears to impair brain function more severely in women compared to men.
In essence, certain risk factors may hold different significance for the female versus the male brain, a distinction that carries implications for dementia research and treatment.
It is widely acknowledged that dementia affects women more frequently than men, and a longer average lifespan does not fully account for this disparity.
Something else is at play, and these latest results may shed light on this as well.
“Our study suggests that women may be at greater risk of dementia because they experience more risk factors, and because these risk factors reduce cognitive function more than they do in men,” the researchers state.
Co-authors Megan Fitzhugh and Judy Pa, neuroscientists at the University of California, San Diego, assert that their findings offer further evidence for the need to assess and manage dementia risk on an individual basis.
“Beyond identifying the most common risk factors, we found that some exert a disproportionately larger impact on women’s cognition,” Fitzhugh commented. “This suggests that preventative strategies could be more effective if tailored not only to the prevalence of risk factors but also to how strongly each factor affects cognition in women versus men.”
The researchers examined health data from 17,182 individuals aged 40 and older, investigating 13 dementia-related risk factors.
Sample sizes varied for each risk factor due to missing data.
Depression, physical inactivity, and sleep disturbances were more prevalent in women than in men.
Conversely, higher rates of hearing loss, diabetes, and alcohol misuse were more commonly observed in men.
Several risk factors were associated with a more substantial decline in cognitive performance among women, indicating a more detrimental effect on the female brain compared to the male brain.
These factors included high blood pressure, hearing loss, and diabetes.
A higher Body Mass Index (BMI) was also linked to poorer cognitive outcomes in women aged 50-60, but not in older age groups.
Three line graphs illustrate the relationship between BMI and cognitive performance for women and men at ages 55, 65, and 75. At ages 55 and 65, elevated BMI correlated with lower cognitive function in women but higher function in men. By age 75, the gender difference diminished considerably, with broad overlap in the uncertainty bands.
Amidst this pattern of cognitive decline, some positive trends emerged, suggesting certain factors might contribute to cognitive preservation in women relative to men.
“Two risk factors—years of education and total cholesterol levels—showed a positive association with cognitive function, with higher levels correlating with better cognitive abilities,” the researchers wrote.
Given their link to cognition, it is plausible that these factors are particularly important for exploration within the context of dementia risk for women.
However, this observational study cannot establish causality. Further longitudinal analysis could provide more compelling evidence that these risk factors influenced cognitive test results.
“It is important to distinguish between sex differences in the prevalence of risk factors and their influence on cognition, as prevalence and influence may not align,” the researchers noted. “Targeting only the most common risk factors within each sex group could lead to overlooking certain risk factors that have a more substantial impact on cognitive decline.”
The new data align with prior research suggesting that dementia risk factors may exert differential effects on men and women, though previous studies typically focused on only one risk factor at a time.
It is estimated that Alzheimer’s disease currently affects one in nine US adults aged 65 and older, with women comprising two-thirds of those affected.
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