A comprehensive review conducted by researchers at University College London (UCL) has found no evidence that menopause hormone therapy (MHT) affects the risk of developing dementia in post-menopausal women. The study, published in The Lancet Healthy Longevity and commissioned by the World Health Organisation (WHO), aims to clarify a long-standing debate over the potential cognitive impacts of hormone replacement therapy (HRT).
The findings come at a crucial time, following the U.S. Food and Drug Administration’s (FDA) November decision to remove ‘black box’ warnings from HRT products. These warnings previously suggested a possible link between HRT and increased dementia risk, which the latest research does not support. Instead, the study emphasizes that MHT should be used based on its perceived benefits and risks, rather than as a preventative measure against dementia.
Comprehensive Analysis of Existing Research
This new systematic review and meta-analysis is touted as the most thorough examination of the relationship between MHT and dementia risk to date. It synthesizes data from over one million participants, including one randomized controlled trial and nine observational studies. The international research team, spanning the UK, Ireland, Switzerland, Australia, and China, found no significant association between MHT and the risk of dementia or mild cognitive impairment.
Lead author Melissa Melville, a PhD student at UCL, highlighted the global significance of the findings, stating, “Across the globe, dementia disproportionately affects women, even after accounting for women’s longer lifespans, so there’s a pressing need to understand what might be driving that risk, and to identify ways to reduce women’s risk of dementia.”
Expert Opinions and Future Guidelines
Senior author Professor Aimee Spector from UCL commented on the implications for clinical practice and policy. “Currently, the World Health Organisation provides no guidance on menopause hormone therapy and cognitive outcomes, leaving a critical gap for clinicians and policymakers,” she said. “To cut through the noise, we reviewed the most rigorous research there is on the subject and found that menopause hormone therapy does not appear to impact dementia risk either positively or negatively.”
This review is expected to inform upcoming WHO guidelines on reducing cognitive decline and dementia risks, anticipated for release in 2026. However, the researchers stress the need for further high-quality, long-term studies, especially focusing on women from ethnic minority backgrounds or those experiencing early menopause or premature ovarian insufficiency.
Historical Context and Ongoing Debate
The debate over MHT’s safety has been ongoing for decades. Historically, hormone therapy was widely prescribed to manage menopausal symptoms, but concerns about its long-term health impacts, including cancer and cardiovascular risks, led to a decline in its use. The recent FDA announcement and this study’s findings may help shift the narrative once more, emphasizing the importance of individualized treatment plans.
According to the study, additional analyses of subgroups based on timing, duration, and type of MHT still did not reveal any significant effects on dementia risk. However, the researchers caution that the scarcity of relevant randomized controlled trials and the relatively low certainty of existing evidence necessitate continued research.
“This review will help to inform the upcoming WHO guidelines on reducing the risk of cognitive decline and dementia, which are expected to be released in 2026,” said Professor Spector.
Looking Ahead: The Need for More Research
While the study provides significant insights, it also underscores the ongoing need for research. The researchers call for more high-quality, long-term studies to fully understand the impacts of MHT, particularly in diverse populations. This call to action is crucial as the global population ages and the prevalence of dementia continues to rise.
As the medical community awaits further guidance from the WHO, the current findings offer a moment of clarity in the complex landscape of women’s health, reaffirming that decisions around MHT should be carefully tailored to each individual’s health profile and needs.
