Study: Women Make Up Two-Thirds of Alzheimer’s Cases. Standard Tests Are Still Designed Around Men.
Women account for nearly two-thirds of all Alzheimer’s cases in the United States, a disparity that has been documented for decades. Yet the standard cognitive tests used to screen for the disease were largely developed and validated in men. Growing evidence suggests these tests may be systematically underdetecting Alzheimer’s in women at the stage when intervention could matter most.
The reason has to do with how women’s brains respond to early disease. Research has found that women tend to have stronger verbal memory and language skills on average, which means that on tests heavily weighted toward those abilities, women can score in the normal range even when Alzheimer’s pathology is already present. Their brains are, in effect, compensating for the disease, and the standard tools are not designed to catch that.
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This matters practically. The newer Alzheimer’s treatments, including drugs approved by the FDA in recent years that target amyloid plaques, have shown the clearest benefit in patients at early stages of the disease. If women are consistently reaching diagnosis later than their disease actually warrants, they may be missing the window where those treatments are most effective.
Researchers have proposed using biomarker-based screening alongside or instead of cognitive tests for women considered at higher risk. Blood tests measuring levels of certain proteins, including p-tau217, which has been studied as an early marker of Alzheimer’s pathology, have shown promise for flagging women at elevated risk long before symptoms appear. A JAMA Network Open study analyzing blood samples from nearly 2,800 women collected in the late 1990s found that higher levels of p-tau217 were strongly associated with dementia diagnosed up to 25 years later.
Biology also plays a role in why women’s Alzheimer’s risk is higher to begin with. Women live longer than men on average, and age is the largest single risk factor for the disease. But longevity does not fully explain the disparity. Hormonal changes around menopause appear to affect brain health in ways researchers are still working to understand, and some studies have found that the drop in estrogen at menopause is associated with changes in brain metabolism that may increase susceptibility to Alzheimer’s pathology.
The clinical infrastructure has not kept pace with this evidence. Most standard dementia screening still relies on tests that were not developed with sex differences in mind. Changing that requires both updated diagnostic tools and a willingness among clinicians to consider that a normal test score in a woman at high risk may not actually mean what it appears to mean.
Sources: Alzheimer’s Association (2024 Alzheimer’s Disease Facts and Figures); JAMA Network Open; research on sex differences in Alzheimer’s cognitive screening and biomarker detection.