Landmark Study: Estrogen Therapy Reduces Dementia Risk by 39%
A groundbreaking study published on August 12, 2026, in Neurology — the medical journal of the American Academy of Neurology — has discovered that women who used estrogen-only menopausal hormone therapy had significantly lower odds of developing dementia and Alzheimer’s disease. The Stanford Medicine-led research, the largest of its kind, analyzed data from 21,462 women and is the first study to directly measure the link between hormone therapy and Alzheimer’s-related deposits in autopsied brain tissue.
According to the findings, estrogen-only hormone therapy users had 39% lower odds of receiving a clinical dementia diagnosis during their lifetimes and 35% lower odds of Alzheimer’s-related brain changes — including amyloid plaques and tau tangles — at autopsy. Users also showed biomarker profiles consistent with less cerebral amyloid accumulation, a hallmark of Alzheimer’s progression.
Researchers were careful to note that the study is observational and cannot prove that estrogen therapy causes the protective effect. “While these findings help us better understand the relationship between hormone therapy use and various markers of dementia, more research needs to be done before we can make recommendations to women,” said lead author Dr. Jennifer Bruno of Stanford Medicine. Notably, about two-thirds of Alzheimer’s patients are women, making these results especially significant for women’s health. The study was supported by the National Institute on Aging.