Women who start common hormone therapy in their 50s may have 23% lower dementia risk
Hormone Replacement Therapy May Lower Dementia Risk for Some Women, Study Finds
A large-scale study of British women suggests that starting hormone replacement therapy during middle age could offer meaningful protection against dementia, though researchers caution the findings represent an association rather than proof of prevention.
The study, published in the journal Alzheimer's & Dementia, examined health records from 183,450 postmenopausal women in the UK Biobank database. The participants, whose average age was 60, were tracked over a 13-year period.
Researchers found that women who used hormone replacement therapy experienced roughly a 10 percent lower risk of developing any form of dementia compared to those who never used the treatment. The protective effect was even more pronounced against Alzheimer's disease specifically, with HRT users showing a 16 percent reduction in risk.
The timing of when women began HRT appeared to matter significantly. The strongest associations emerged among those who started treatment between ages 46 and 56. Women who initiated therapy after age 56, however, did not demonstrate the same reduced risk profile.
Surgical menopause presented another factor linked to greater benefit. Women who underwent ovary removal surgery and subsequently began HRT showed particularly notable reductions in dementia risk, potentially because their bodies experienced a more sudden drop in hormone levels.
Dr. Alexa Fiffick, a family medicine physician at Concierge Medicine of Westlake in Cleveland, Ohio, who was not involved in the research, said the study adds to ongoing scientific discussions but stops short of establishing definitive causation.
"The data has been at this point for a while—there's no definitive evidence that hormone therapy prevents dementia," Fiffick said. "However, if you're having symptoms, if you feel not yourself, come in, talk to your doctor, have that conversation."
The research team acknowledged numerous limitations in their analysis. The study population consisted predominantly of women with European ancestry who tended to have higher socioeconomic status, meaning the results may not translate equally to other demographic groups. Additionally, researchers lacked detailed information about specific hormone formulations, dosages, or methods of administration.
The study also could not account for unmeasured differences between HRT users and non-users, such as overall health habits, diet, exercise, or broader access to medical care—all factors that independently influence dementia risk.
Fiffick noted that while the research offers intriguing signals, women should not pursue HRT solely for dementia prevention purposes.
"It's worth the conversation, it's worth bringing up, but I wouldn't go out of your way for just this purpose," she said. "It's not one size fits all, and it's really worth an extensive conversation."
The findings do align with emerging evidence linking menopausal symptoms like hot flashes and night sweats to vascular changes in the brain that may contribute to cognitive decline. Fiffick expressed cautious optimism that addressing these symptoms might ultimately prove protective against dementia, though current data remains insufficient.
Researchers announced plans to conduct randomized controlled trials to move beyond observational associations. Future studies will examine variables including estrogen-only versus combined hormone formulations, specific dosages, delivery methods, treatment duration, and genetic factors like APOE ε4 status, which is known to increase Alzheimer's risk.
"Women deserve to have information to use to make decisions about their bodies," Fiffick said. "I think the more we have studies like this, the more we're going to propel forward the randomized controlled trials to really give women the data they deserve."