Roughly two out of every three people diagnosed with dementia are women. That statistic surprises most people when they first encounter it, and the explanation turns out to be more complicated than the one usually offered.
The standard answer is that women live longer, and since age is the largest risk factor for dementia, more women survive into the years when it becomes common. That explanation is true and it accounts for a substantial portion of the gap. But the research over the past decade has made clear that longevity alone does not explain everything, and that there are biological, medical, and social factors that also contribute.
Here is what the evidence shows.
The Longevity Explanation
Age is by far the strongest risk factor for dementia. Prevalence roughly doubles every five years after age 65. Women in most countries outlive men by several years on average, which means substantially more women reach the ages at which dementia risk is highest.
This is the primary driver of the gap and it should not be understated. It also means that some of what looks like a sex difference in risk is actually a difference in survival. Men who die in their seventies from cardiovascular disease never reach the age at which they might have developed dementia.
That said, several lines of evidence indicate that longevity is not the whole story.
Alzheimer’s Specifically, and Not Other Dementias
One of the clearest signals that something beyond longevity is at work is the distribution across dementia subtypes.
Alzheimer’s disease, the most common form, affects roughly twice as many women as men. But other forms of dementia, including vascular dementia, dementia with Lewy bodies, and frontotemporal dementia, are more common in men. If the gap were purely a function of women living longer, you would expect women to be overrepresented across all types of dementia rather than concentrated in one.
This subtype-specific pattern has directed a great deal of research toward what is biologically distinct about Alzheimer’s disease and about female physiology.
The Menopause Hypothesis
The most studied biological explanation involves estrogen and the hormonal transition of menopause.
Estrogen appears to have several protective effects on the brain. It supports glucose metabolism in neurons, has anti-inflammatory properties, influences synaptic plasticity, and appears to interfere with some of the processes involved in amyloid accumulation. During menopause, estrogen levels fall dramatically over a relatively compressed period in late middle age.
Neuroimaging research led by Lisa Mosconi and colleagues has documented measurable changes in the brains of women during the menopausal transition, including reductions in brain glucose metabolism and gray matter volume, along with increases in amyloid deposition in some women. These changes occur decades before dementia symptoms would typically appear, which is consistent with what we know about the long preclinical phase of Alzheimer’s disease.
The hypothesis is that the menopausal transition represents a window of increased vulnerability during which the brain undergoes metabolic changes that may set the stage for later neurodegeneration in some women. This remains an active area of research and the picture is not yet settled, particularly regarding whether hormone therapy alters the risk and if so, under what timing and circumstances.
Genetics and the X Chromosome
Genetic factors also appear to differ by sex.
The APOE e4 variant, the most significant common genetic risk factor for late-onset Alzheimer’s disease, appears to confer greater risk in women than in men. Multiple studies have found that women carrying a single copy of APOE e4 have a higher risk of developing Alzheimer’s than men carrying the same variant, particularly between the ages of roughly 65 and 75.
More recently, research has turned to the X chromosome itself. A 2024 study published in JAMA
Neurology by Belloy and colleagues examined the role of X chromosome genetics in
Alzheimer’s disease, an area that has historically been excluded from large genetic analyses for methodological reasons. Because women have two X chromosomes and men have one,
X-linked genetic factors could plausibly contribute to sex differences in risk. This line of research is relatively new and its findings are still developing.
Differences in How the Disease Progresses
Sex differences appear not only in who develops dementia but in how it manifests.
A 2024 narrative review published in Alzheimer’s & Dementia by Arenaza-Urquijo and colleagues, produced by an Alzheimer’s Association special interest group examining sex and gender differences in cognitive resilience, found evidence that women with mild cognitive impairment showed greater cognitive decline than men, and that women with Alzheimer’s dementia performed worse than men across multiple cognitive domains including visuospatial ability, verbal processing, and semantic and episodic memory.
There is also evidence for a phenomenon sometimes described as female cognitive reserve in verbal domains. Women tend to outperform men on verbal memory tests throughout life, which can mask early Alzheimer’s pathology on standard cognitive screening. A woman with significant underlying disease may still score in the normal range on tests that rely heavily on verbal memory, leading to later diagnosis and a more advanced disease state at the time of detection.
Social and Structural Factors
Not all of the difference is biological.
Education and occupation. Cognitive reserve, the brain’s resilience to damage, is built partly through education and cognitively demanding work. Women in the generations currently reaching the age of dementia risk had substantially less access to higher education and professional careers than men of the same cohorts. Lower educational attainment is one of the modifiable risk factors identified by the Lancet Commission, and the historical education gap likely contributes to the current dementia gap.
Social isolation and widowhood. Because women typically outlive their partners, they are more likely to live alone and experience prolonged loneliness in later life. Social isolation is an established modifiable risk factor for dementia, as covered elsewhere in this blog series.
Cardiovascular risk. Some cardiovascular risk factors that contribute to dementia risk, including hypertension, appear to affect women differently, and women who develop high blood pressure in middle age may face elevated dementia risk relative to men with comparable readings.
Caregiving burden. Women are disproportionately the caregivers for people with dementia, and chronic caregiving stress is itself associated with adverse health outcomes including cognitive effects.
Differences in Care and Treatment
The disparities extend beyond risk into how dementia is diagnosed and treated.
A 2025 scoping review published in Archives of Public Health by Aguzzoli and colleagues examined sex and gender differences in access, quality of care, and treatment effectiveness in dementia, reviewing studies through 2024. The review found meaningful differences between men and women in access to diagnosis, in treatment, and in quality of care.
Among the findings: women were prescribed antipsychotic and other psychotropic medications for longer periods than men, a finding worth noting given the known risks of long-term antipsychotic use in dementia. Cognitive stimulation therapy showed greater cognitive improvements in women. Exercise interventions showed a possibly more pronounced effect in women, though the data were limited. And clinical trials of disease-modifying therapies suggested that women may be less responsive to these treatments than men, a finding with significant implications as new Alzheimer’s drugs enter clinical use.
The review’s overall conclusion was that these differences can meaningfully affect health outcomes and that sex and gender should be explicitly considered in healthcare planning and clinical trial design.
What This Means Practically
For women and their families, a few things follow from this research.
Cognitive screening deserves attention even when standard tests come back normal, particularly if there are subjective concerns about memory. The verbal reserve effect means brief screening tools may underdetect early Alzheimer’s in women.
Modifiable risk factors deserve the same attention they would receive for anyone, and possibly more given the elevated baseline risk. Cardiovascular health, physical activity, hearing, social engagement, and sleep are all areas where the evidence supports meaningful risk reduction.
The menopause research is worth following but is not yet at the point of clear clinical recommendations. Decisions about hormone therapy involve multiple considerations beyond cognitive risk and should be made with a physician who knows the individual’s full medical picture.
Finally, the disparities in care documented in the 2025 scoping review are worth knowing about as a patient or family member. Asking questions about medication duration, particularly with antipsychotics, and advocating for thorough diagnostic evaluation are reasonable steps.
Several of the factors discussed here, including social isolation, appear repeatedly across dementia risk research. Our post on loneliness as a medical risk factor for dementia covers the evidence on social isolation in more depth, including the biological mechanisms through which it appears to affect the brain.
Have questions about memory care for a loved one?
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Sources
- Arenaza-Urquijo EM, et al. Sex and gender differences in cognitive resilience to aging and Alzheimer’s disease. Alzheimer’s & Dementia. 2024;20(8):5695-5719.
- Aguzzoli E, Walbaum M, Knapp M, Castro-Aldrete L, Santuccione Chadha A, Cyhlarova E. Sex and gender differences in access, quality of care, and effectiveness of treatment in dementia: a scoping review of studies up to 2024. Archives of Public Health. 2025;83:132.
- Belloy ME, et al. Role of the X Chromosome in Alzheimer Disease Genetics. JAMA Neurology. 2024;81(10):1032-1042.
- Mosconi L, et al. Menopause impacts human brain structure, connectivity, energy metabolism, and amyloid-beta deposition. Scientific Reports. 2021;11:10867.
- Livingston G, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet. 2024;404(10452):572-628.
- Alzheimer’s Association. 2025 Alzheimer’s Disease Facts and Figures. Alzheimer’s & Dementia. 2025.