Estrogen-only menopausal hormone therapy associated with 35% lower odds of Alzheimer's pathology in autopsy cohort

The study examined two large databases of deceased women, scoring amyloid plaques, neurofibrillary tangles, and plaque density. Estrogen-only users showed statistically lower pathology scores after adjustment for age, APOE4 status, hypertension, education, and race. Living-participant data from the same cohorts indicated 39% lower clinical dementia odds and better memory and functional scores among users. The design remains observational; hysterectomy status was inferred rather than directly verified for all participants.

Prior observational work and the Women's Health Initiative produced conflicting dementia signals, often with combined estrogen-progestin regimens. This analysis isolates estrogen-only exposure and substitutes autopsy endpoints for clinical diagnoses, addressing misclassification noted by the authors. It does not establish causation or rule out healthy-user bias in women selected for hysterectomy and subsequent therapy.

No randomized trial has yet tested estrogen-only therapy against Alzheimer's pathology or incidence as a primary endpoint. Future studies require prospective randomization in hysterectomized women, longitudinal biomarker and imaging confirmation, and sufficient follow-up to detect divergence in clinical dementia rates.

Evidence quality is moderate: large autopsy series with multiple Alzheimer's outcomes but limited by observational design, potential confounding, and restriction to estrogen-only regimens.