Key Takeaway:
- HRT was linked to lower risk: Users had about 10% lower dementia risk and 16% lower Alzheimer’s risk.
- Timing may matter: Starting HRT between ages 46 and 56 showed the strongest association.
- More research is needed: The observational study cannot prove HRT prevents dementia.
A large U.K. study examining HRT and dementia risk found that postmenopausal women who used hormone replacement therapy had lower dementia risk, particularly when treatment began earlier and after surgical menopause.
Large study finds lower dementia risk
Researchers analyzed medical records from more than 183,000 postmenopausal women in the U.K. Biobank who were followed for an average of 13 years. The study was published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
Women who had used hormone replacement therapy, or HRT, had about a 10% lower risk of dementia and a 16% lower risk of Alzheimer’s disease compared with women who had not used HRT, the researchers found.
The association between HRT and dementia risk varied according to when women began treatment and other biological factors. Women who started HRT between ages 46 and 56 showed the greatest reduction in dementia risk.
The researchers also found stronger associations among women who experienced surgical menopause rather than natural menopause and among carriers of the APOE4 gene, which is associated with increased Alzheimer’s risk.
Anne-Marie Minihane, lead author of the study and a professor of nutrigenomics at the University of East Anglia’s Norwich Medical School, said the findings add to evidence that HRT’s effects on brain health vary among women.
“While HRT has long been prescribed primarily to relieve menopausal symptoms,” Minihane said, “this work suggests it may also play a role in long-term cognitive health for some women.”
Experts urge caution over HRT findings
Menopause has been associated with changes that may affect brain health, including estrogen loss, changes in brain structure, sleep problems and metabolic changes. Women also account for about two-thirds of people living with dementia globally, according to the World Health Organization.
Sherry Ross, an OB/GYN and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California, said the study is notable because of its large population and long follow-up period.
Ross, who was not involved in the research, said changes in gray matter during menopause may affect functions including memory, attention, decision-making and emotion regulation. She suggested that starting estrogen early in the menopause transition could potentially limit some of those changes.
Prudence Hall, an OB/GYN in Santa Monica, said brain fog and short-term memory problems are common concerns among women during perimenopause and menopause.
Hall, who was also not involved in the study, said many women report improved brain function while taking HRT. She emphasized the importance of addressing dementia risk factors during menopause through medical care and lifestyle changes.
Researchers say more trials are needed
Despite the findings, experts caution that the study cannot establish that HRT prevents dementia. Because researchers observed existing medical data rather than randomly assigning women to treatment, other factors could explain part of the association.
Dung Trinh, an internist with MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic in Irvine, California, called the findings encouraging but said women should not start HRT solely to prevent dementia.
“It cannot prove that HRT itself prevented dementia,” Trinh said, adding that he would not recommend HRT for dementia prevention based on the study alone.
Trinh said future research should compare different HRT formulations, including estrogen alone and estrogen with a progestogen, as well as different doses, treatment methods and durations.
Researchers also need to examine natural and surgical menopause separately and account for genetic factors such as APOE4, he said.
The findings on HRT and dementia risk suggest that when HRT is started and which women receive it may matter, but randomized studies are needed before HRT can be considered a strategy for preventing dementia.
