Women who enter menopause earlier in life may face a higher risk of developing dementia later on, according to a new international study led by the University of Galway in collaboration with Boston University.
The study, published in the Journal of Alzheimer’s Disease, analyzed long-term data from more than 1,300 women participating in the Framingham Heart Study — the world’s longest-running health study. Researchers found that the age at which a woman reaches menopause, her exposure to estrogen over her lifetime, and whether she uses hormone replacement therapy (HRT) after menopause all appear to influence brain health and cognitive function.
Earlier Menopause, Greater Dementia Risk
The researchers discovered that women who entered menopause at a younger age were more likely to experience cognitive decline and develop dementia later in life. In contrast, women who experienced menopause later, or who had longer exposure to estrogen throughout their reproductive years, showed stronger cognitive performance and healthier brain scans.
“Entering menopause at an earlier age appears to be associated with an increased risk of dementia,” said Professor Emer McGrath, the study’s lead author and a neurologist at Galway University Hospital. “Meanwhile, post-menopause hormone replacement therapy appears to be associated with a lower risk.”
Hormone Therapy and Brain Health
The findings suggest that estrogen — the primary female sex hormone — may play a protective role in brain health. Women who used hormone replacement therapy after menopause had lower dementia risk and showed better cognitive test scores in areas such as reasoning, memory, and visuospatial skills, which involve understanding and manipulating visual information.
The study also found that women with higher blood estrogen levels, more children, and a later age at menopause tended to have larger brain volumes — particularly in regions that often shrink in Alzheimer’s disease.
However, Professor McGrath cautioned that while these results are encouraging, they do not prove that HRT directly prevents dementia. “Our findings suggest positive cognitive benefits of greater lifetime estrogen exposure,” she said. “But more research is needed to fully understand the relationship.”
Why Women Face Higher Dementia Risk
Women make up nearly two-thirds of Alzheimer’s disease cases worldwide. While longer life expectancy partly explains this imbalance, researchers say biological factors — including hormonal changes and reproductive history — may also play key roles.
Despite growing awareness of gender differences in brain aging, experts note that research into how reproductive health affects dementia risk has lagged behind other fields like cardiovascular medicine. Understanding how hormonal shifts impact the brain could help develop targeted strategies to protect women’s cognitive health as they age.
A Closer Look at the Study
The research team analyzed reproductive and hormonal factors across each woman’s lifespan, including:
- Age at first menstruation and at menopause
- Duration of the reproductive years
- Estrogen levels in the blood
- Use of post-menopausal hormone therapy
They then linked these factors to performance on cognitive tests and MRI scans measuring brain volume. The women were followed over time to track whether they developed dementia.
The findings add to a growing body of evidence suggesting that the hormonal transitions women experience — especially during menopause — may influence long-term brain health.
What This Means for Women
While menopause is a natural phase of aging, the study underscores the importance of monitoring cognitive and hormonal health during midlife and beyond. Women who enter menopause earlier than average — typically before age 45 — may benefit from discussing brain health and hormone therapy options with their healthcare providers.
“Understanding how female hormones affect the brain could help us find new ways to protect women from dementia,” McGrath said. “This study brings us one step closer to that goal.”
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