Scientists from Mayo Clinic and Harvard Medical School studied whether hormone therapy used during menopause might be linked to dementia and Alzheimer’s disease. The researchers did not advise stopping hormone use; they emphasized this study shows a correlation, not proof of cause, and individual medical advice remains essential. The investigation was published in BMJ.
Hormone replacement therapy (HRT) is commonly used to ease menopause symptoms such as hot flashes and night sweats. Treatments include estrogen-only options or regimens combining estrogen with progestin, along with skin patches, gels, and creams that deliver hormones through the skin.
For the study, data were drawn from single-country records, including 5,500 women with dementia and 55,900 women without dementia, spanning 2000 to 2018. All participants lived in Denmark and were between 50 and 60 years old at the start of the period. Researchers also considered other dementia risk factors, such as income, education quality, hypertension, diabetes, and thyroid disease.
The analysis found that women who used a combined estrogen and progestin therapy had about a 24% higher incidence of various dementia types, including Alzheimer’s disease, compared with women who did not use hormones for menopause.
Longer exposure mattered: women who used hormones for 12 years or more faced roughly a 74% higher risk of developing dementia than non-users. Using hormones for one year or less was associated with about a 21% increased risk. The elevated risk was especially pronounced in women under 55.
The study found similar increases in risk for both continuous (daily estrogen with progestin) and cyclical (daily estrogen with progestin for 10 to 14 days each month) regimens.
The authors stressed that the findings show a correlation, not a causal link. They also noted that a predisposition to dementia could exist in some women undergoing hormonal therapy, and that these results should not be taken as evidence that hormones cause dementia. Because of these caveats, the study should not replace medical guidance from a health professional.
Earlier observations suggested that high doses of vitamin D might lower the risk of atrial fibrillation in older adults, a finding separate from the menopause and dementia discussion.