Dementia is often described as a disease of aging that affects everyone equally over time. However, the statistics show a different picture. Of the seven million Americans living with Alzheimer’s disease, almost two-thirds are women. A woman’s lifetime risk of developing dementia is about 20%, while for men it is only 10%. This difference is not simply because women tend to live longer; the gap remains even after researchers adjust for lifespan.
Why are women more at risk? A team of researchers from the University of California, San Diego, aimed to answer this in a new study published in Biology of Sex Differences. Their results provide strong evidence that the gender gap in dementia comes from two main reasons: women have more risk factors for dementia, and these risk factors have a greater impact on their brains.
What the Study Did
Researchers Megan Fitzhugh and Judy Pa analyzed data from the Health and Retirement Study, which follows a large, nationally representative group of older adults in the United States. Their study included 17,182 participants with an average age of 69, of whom 59% were women.
They looked at 13 risk factors that can be changed, as identified by the Lancet Commission on Dementia Prevention. These include years of education, hearing loss, total cholesterol, depression, lack of physical activity, diabetes, smoking, high blood pressure, obesity (measured by BMI), drinking too much alcohol, social isolation, poor vision, and poor sleep.
For each risk factor, the team checked two things: how common it was in women compared to men, and how much each factor affected thinking skills. They measured this using a standard test that included memory, math, and counting backward.
The Findings: Women Are Carrying More of the Burden
The results were clear. Out of the 13 risk factors, women had much higher rates for seven of them. Men had higher rates for only three.
Risk factors are more prevalent in women:
- Depression (17% of women vs. 9% of men)
- Physical inactivity (48% vs. 42%)
- Poor sleep (45% vs. 40%)
- Elevated total cholesterol
- Smoking (26% vs. 20% among those with available data)
- Poor vision
- Fewer years of education
Risk factors are more prevalent in men:
- Hearing loss (64% vs. 50%)
- Diabetes (24% vs. 21%)
- Excessive alcohol use (22% vs. 12%)
Hypertension showed an interesting age-related pattern. It was a bit more common in men under 65, but after age 65, it became much more common in women. This change may be related to hormonal shifts during and after menopause.
Overall, women tend to have more active dementia risk factors than men of the same age. This is already a concern, but the next findings from the study make the situation even more serious.
Not Just More Risk Factors Harder-Hitting Ones
When the researchers examined how each risk factor affected cognitive test scores, they found that the same risk factor consistently caused greater cognitive impairment in women than in men.
Hearing loss happened more often in men, but it affected women’s thinking skills almost twice as much. Women with hearing loss scored much lower on cognitive tests than men with the same level of hearing loss.
Diabetes was also more common in men, but it had a much bigger effect on women’s thinking skills. Women with diabetes had much lower cognitive scores than men with diabetes. This matches other research showing that women with type 2 diabetes experience faster cognitive decline over time.
Hypertension was associated with worse cognitive outcomes across both sexes, but the negative effect was meaningfully larger in women. This may be related to women’s greater susceptibility to hypertension-related small vessel disease in the brain, damage to the tiny arteries that supply white matter, as well as cardiovascular changes associated with the menopausal transition and pregnancy complications such as gestational hypertension.
BMI showed a particularly nuanced pattern. Higher BMI was associated with poorer cognitive scores in women at ages 55 and 65, while the same relationship did not hold and even trended in the opposite direction in men at those ages. This sex-specific effect largely disappeared by age 75, which aligns with the well-documented obesity paradox, in which excess weight in midlife appears to raise dementia risk, whereas higher body weight in later life may have protective effects for both sexes. The midlife window, however, appears to be a period of heightened vulnerability, specifically for women, possibly due to the metabolic disruptions associated with perimenopause.
On a positive note, two risk factors were linked to better thinking skills, and both effects were stronger in women. Higher education and higher total cholesterol were each associated with better cognitive scores, especially among women. This suggests that education is a particularly strong protective factor for women’s brain health.
The Compounding Effect: More Risk Factors, Steeper Decline
Beyond individual risk factors, the study also looked at what happens when risk factors pile up. The results were sobering. Both women and men showed declining cognitive scores as their number of risk factors increased, but the rate of decline was steeper in women. Each additional risk factor carried a heavier cognitive penalty for women than for men.
This compounding effect is clinically significant. It suggests that women’s elevated dementia risk is not just the sum of their individual risk factors; those risk factors interact and amplify each other’s effects in ways that are particularly damaging to the female brain. The underlying biology remains poorly understood, but hormonal shifts across the lifespan, differences in cardiovascular physiology, and greater susceptibility to certain forms of brain inflammation are likely contributors.
What This Means for Prevention
The study’s authors make it clear that these findings should not lead to hopelessness. Instead, they offer a guide for targeted prevention. The main message is that strategies to reduce dementia risk should be tailored not only to each person, but also to their sex.
Crucially, the researchers emphasize that focusing solely on the most common risk factors among women is insufficient. Some risk factors that are more prevalent in men, such as hearing loss, have a disproportionately large cognitive impact in women. A woman who develops hearing loss may face a steeper cognitive trajectory than a man with the same condition, which means early intervention for hearing loss in women could be especially valuable.
Based on the study’s findings, women in particular may benefit from prioritizing:
Management of hypertension, especially in midlife and the years surrounding menopause, given the strong association between high blood pressure and greater cognitive decline in women. Regular blood pressure monitoring and lifestyle or pharmacological management, where appropriate, are well within reach for most people.
Blood sugar regulation, with attention to diabetes risk and management, given that diabetes appears to extract a steeper cognitive toll in women than men across the lifespan.
Hearing health, even for women who may not currently consider themselves to be at high risk for hearing loss. Given the asymmetric cognitive impact of hearing loss in women, early assessment and intervention, including hearing aids when appropriate, may be more protective than previously appreciated.
Sleep quality, given that poor sleep was more prevalent in women, is increasingly recognized as both a risk factor and an early warning signal for dementia. Addressing insomnia, sleep apnoea, and disrupted sleep architecture may have real downstream benefits for cognitive aging.
Physical activity, which reduces the risk of several risk factors simultaneously, including hypertension, diabetes, obesity, depression, and social isolation, has direct neuroprotective effects.
Given the stronger cognitive protection that education appears to provide in women, continued intellectual engagement throughout life may offer meaningful brain health benefits.
The Bottom Line
This study, drawing on one of the largest and most representative datasets of older Americans, provides compelling evidence that the dementia gender gap is both real and addressable. Women face a higher dementia risk not because their biology is inherently more fragile, but because they accumulate more modifiable risk factors and because those risk factors have a more powerful effect on their cognition. Both of those drivers are, at least in part, changeable. Understanding the specific risk profile that matters most for women’s brain health is the first step toward building prevention strategies that can genuinely close the gap.
Reference
Fitzhugh, M. C., & Pa, J. (2026). Sex differences in modifiable risk factors of dementia and their associations with cognition. Biology of Sex Differences, 17, 110. https://doi.org/10.1186/s13293-026-00908-7