Women taking estrogen had fewer signs of Alzheimer’s in their brains
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- Researchers analyzing data from 21,462 women found estrogen-only hormone therapy was linked to 39% lower odds of a dementia diagnosis and 35% lower odds of Alzheimer's-related brain changes at autopsy, including amyloid plaques and tau tangles
- Jennifer Bruno, PhD, of Stanford Medicine led the study published August 12, 2026 in Neurology, the journal of the American Academy of Neurology, emphasizing the findings show an association and not causation
- Autopsy results showed 18% of hormone therapy users had no signs of Alzheimer's disease compared to 10% of non-users, while only 40% of users showed all three pathology signs versus 51% of non-users
- Biomarker tests from blood and spinal fluid showed women who used hormone therapy had amyloid levels consistent with less amyloid plaque accumulating in the brain
- The study population began hormone therapy at an average age of 70 — far later than current medical practice, which typically calls for starting in the late 40s to early 50s and stopping before age 60
- The analysis focused exclusively on estrogen-only therapy, since prior research had suggested combining estrogen with progestin may raise dementia risk; under current standards, estrogen-only is prescribed only to women who have had a hysterectomy
- The study was supported by the National Institute on Aging and followed participants for an average of three to five years
Why it matters: For women who have had hysterectomies and are weighing estrogen-only therapy, the study adds a notable data point on long-term brain health — but Bruno cautioned the results may not apply to women on today's regimens, which begin treatment roughly two decades earlier than the women in this study did.
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