Hormone replacement therapy during menopause is linked to a reduced risk of dementia and Alzheimer's disease in women, according to a study by British scientists.
The study, published in the medical journal Alzheimer's & Dementia, tracked the health of 183,450 postmenopausal women over an average period of 13 years. During the follow-up period, researchers recorded approximately 4,000 cases of dementia among the group.
Women who used hormone replacement therapy for at least one year had an overall dementia risk about 10 per cent lower than those who had never taken the treatment. For Alzheimer's disease specifically, the risk was 16 per cent lower among hormone users compared to non-users.
Hormone replacement therapy, often referred to as HRT, is a medical treatment used to manage symptoms associated with menopause by replacing reproductive hormones, primarily estrogen and progesterone, which decline as women grow older. Dementia is an overarching medical term for progressive decline in memory, thinking, and reasoning skills, with Alzheimer's disease representing the most prevalent cause of cognitive impairment worldwide.
Surgical menopause and genetic risk
The protective connection between hormone intake and reduced dementia risk was particularly pronounced among women who experienced surgical menopause, such as after the surgical removal of their ovaries. Among women who underwent surgical menopause, taking hormones was linked to a 26 per cent lower risk of dementia.
Researchers also found that hormone replacement therapy was more strongly associated with a protective effect in women who had less lifetime exposure to estrogen. The protective link was similarly elevated among women carrying the APOE4 gene variant, which increases the likelihood of developing Alzheimer's disease.
Surgical removal of the ovaries, known medically as an oophorectomy, causes a sudden and steep decline in hormone production compared to the gradual hormone decrease during natural menopause. The APOE4 variant of the apolipoprotein E gene is recognized by medical researchers as a major genetic risk factor for developing late-onset Alzheimer's disease.
Age at treatment onset
The timing of when hormone replacement therapy was initiated was identified as another key factor in the study. The most substantial reduction in dementia risk occurred in women who began taking hormones between the ages of 46 and 56, a period closer to the onset of menopause.
The study authors stressed that their findings do not establish a direct causal link or prove that hormone replacement therapy prevents dementia. Nevertheless, they stated that the statistical outcomes point to potential benefits of hormone therapy for overall brain health.
The findings build on broader research examining factors that influence cognitive decline in older adults. Earlier studies showed that obtaining deep sleep slows the progression of Alzheimer's disease and helps delay memory deterioration.
