An extensive international study led by the University of Galway has identified a significant link between the timing of menopause and women’s risk of dementia, suggesting that reproductive hormones may play an essential role in protecting brain health. The research indicates that women who enter menopause earlier in life are more likely to develop dementia. In contrast, those who receive hormone replacement therapy (HRT) after menopause appear to face a lower risk. The findings were published in the Journal for Alzheimer’s Disease, underscoring growing interest in how hormones influence long-term cognitive decline.
The study was conducted by researchers from the University of Galway, in collaboration with Boston University, and drew on data from 1,329 cognitively healthy women participating in the renowned Framingham Heart Study. This long-running project, which began in 1948, provides an unusually rich dataset for examining how health, lifestyle, and biology intersect over time. For this particular research, scientists focused on a range of reproductive factors: the age at which a woman had her first period, when she reached menopause, the number of years she spent in her reproductive phase, her oestrogen levels, and whether she had received HRT. These elements were then compared with cognitive test results, MRI scans showing changes in brain structure, and the later risk of dementia.
The results revealed several clear patterns. Women who reached menopause at an earlier age were more likely to experience dementia later on, while women who took post-menopausal HRT had a reduced risk. Additionally, more prolonged exposure to oestrogen over a woman’s lifetime appeared to offer cognitive benefits. Those with more years between the onset of menstruation and menopause performed better on tests assessing memory, reasoning, and visuospatial skills—the ability to interpret and work with spatial information. MRI scans also showed that longer reproductive lifespan and higher oestrogen exposure were linked with greater brain volume in regions that typically shrink during Alzheimer’s disease. This suggests that oestrogen may help preserve brain structure and cognitive function.
Interestingly, the study also found that having more children and higher blood oestrogen levels were associated with stronger cognitive performance. Women with more children showed larger brain volumes in areas commonly affected by Alzheimer’s disease. While the reasons for this are not yet fully understood, pregnancy involves repeated periods of high hormone exposure, which may contribute to long-term brain resilience.
Professor Emer McGrath, Associate Professor at the University of Galway and Consultant Neurologist at Galway University Hospital, emphasised that the findings point to a complex relationship between hormones and brain ageing. Although the results suggest that prolonged exposure to oestrogen may protect cognitive health, she cautioned that further research is needed to confirm the associations and determine the best use of hormonal therapies.
Women account for nearly two-thirds of people living with Alzheimer’s disease, yet scientific understanding of sex-specific risk factors remains limited. While longer life expectancy in women partly explains this imbalance, the study highlights that reproductive biology and hormonal changes may also strongly influence brain health. The research underscores the need to consider women’s hormonal history when exploring dementia risk and developing preventative strategies for cognitive ageing.
More information: Emer McGrath et al, The association between reproductive factors and neurocognitive and neuroimaging markers of brain aging, Journal of Alzheimer’s Disease. DOI: 10.1177/13872877251372430
Journal information: Journal of Alzheimer’s Disease Provided by University of Galway
