Scientists found that women’s higher dementia rates aren’t just because they live longer, in data from 22 studies across 18 countries
For years, the standard explanation for why more women than men have dementia has been simple: women live longer, and dementia is mostly a disease of old age. Researchers at the University of New South Wales put that explanation to a global test. They pooled 22 long-term studies that followed tens of thousands of older adults across 18 countries and six continents, counting who developed dementia and when. Then they took age out of the equation.
Women still came out ahead. After standardizing for age, women developed dementia at a rate of 10.6 new cases per 1,000 people per year, compared with 8.6 for men. That is about two extra cases for every 1,000 women each year, a gap that longer lives alone cannot explain.
Across both sexes, the rate was 9.7 new cases per 1,000 people per year. Over 287,632 years of follow-up, 3,001 participants developed dementia.
The question has been surprisingly unsettled. Earlier work has given mixed answers. A study of more than 8 million US Medicare beneficiaries found that men had a higher rate of dementia diagnoses before age 70 and women a higher rate afterward, and noted that results on sex differences at the same age had been inconsistent. The new meta-analysis adds a broader view, drawing on cohorts in high-, middle- and low-income countries and using the same method across all of them.
Each study in the analysis diagnosed dementia clinically rather than relying on records, and the team calculated rates by age and sex before standardizing them to the 2023 world population.
The second finding is about where people live. Dementia incidence was higher in low- and middle-income countries than in high-income ones, which the authors say have been badly underrepresented in past estimates. Using their rates, they estimate that 11.4 million people developed dementia worldwide in 2023, a figure they project will reach 24.7 million new cases a year by 2050 as populations grow and age.
“Greater vigilance in dementia screening among women, alongside the prioritization of women’s brain health and sex-specific risk factors, is needed,” the researchers conclude.
The study did not test why women are more affected. Researchers have proposed several possibilities, including the hormonal changes of menopause and differences in education and health between generations of women and men, but these remain hypotheses. The role of hormones is one of the most debated, as our coverage of hormone therapy and dementia showed.
For women, the practical point is that dementia risk is not just a matter of living longer. Many of the known risk factors, such as high blood pressure, hearing loss, physical inactivity and social isolation, can be addressed at any age, and memory changes are worth raising with a doctor rather than dismissing as normal aging. Once dementia is diagnosed, other surprises can follow, such as the obesity paradox in survival.
There are limits to what this shows. The 22 studies used different methods to identify dementia, and some regions are covered by only a few studies, which makes cross-country comparisons uncertain. The 2050 figure is a projection that assumes today’s age- and sex-specific rates stay the same, not a count of future cases.
Source
Vella AS, Visontay R, Lipnicki DM, et al. “Global Incidence of All-Cause Dementia: A Meta-Analysis.” JAMA Neurology, 2026.
DOI: 10.1001/jamaneurol.2026.3540
Also cited
“Age and Incidence of Dementia Diagnosis.” Journal of General Internal Medicine, 2021.
DOI: 10.1007/s11606-020-05895-y
