Overview
- The study, published Wednesday, Sept. 2, 2026, analyzed 183,450 postmenopausal women in the UK Biobank over about 13 years and found HRT use was associated with roughly a 10% lower risk of all-cause dementia and a 16% lower risk of Alzheimer’s disease.
- Women who began HRT between ages 46 and 56 showed the greatest reduction in dementia risk, and women who had surgical menopause saw the largest association at about a 26% lower risk.
- The analysis is observational so it cannot prove HRT prevents dementia. Researchers warned the association may reflect healthier users or other unmeasured factors rather than a direct protective effect.
- Key data were missing: the study did not record HRT formulation, dose, route, or safety outcomes such as clot risk, and its mostly European, relatively affluent cohort limits how broadly the results can be applied.
- Authors propose randomized controlled trials to test causality and to compare formulations, timing windows, doses, routes and APOE genotype effects, and clinicians advise women not to start HRT solely to prevent dementia but to discuss individual risks and benefits with their doctor.