New research from Stanford University suggests that women who use oestrogen-only hormone replacement therapy (HRT) in later life may have a lower risk of developing physical signs of Alzheimer's disease. The study, published in the journal Neurology, analysed data from over 20,000 women and found a 39% reduction in the likelihood of a clinical dementia diagnosis among those who received this specific treatment compared to non-users.
Study Details and Findings
The researchers examined two extensive American health databases to explore how oestrogen-only HRT influences brain health. Their analysis revealed that women taking the medication experienced a 33% reduction in memory problems and day-to-day cognitive difficulties. Post-mortem brain examinations comparing 258 therapy users against 2,701 non-users demonstrated 35% lower odds of showing biological indicators of Alzheimer's disease, including harmful plaque accumulation.
These findings add to the growing body of research on hormone therapy and dementia risk, but experts caution that the study can only show an association, not causation.
Expert Reactions and Cautions
Dr Tom Blackmore, from Alzheimer's Research UK, reviewed the results and noted: "This study found that women who reported using oestrogen-only hormone therapy at an average age of around 70 were less likely to develop dementia and showed fewer biological signs associated with Alzheimer's disease."
However, he emphasised that "this study can only show an association and cannot tell us whether hormone therapy itself reduced dementia risk. Many factors influence a person's likelihood of developing dementia, and women who received hormone therapy may differ from those who did not in ways that also affect their long-term brain health."
Dr Blackmore also pointed out that the women in the study used oestrogen-only therapy at an average age of around 70, which differs from typical current use of HRT. He explained that oestrogen-only therapy is usually prescribed to women who have had a hysterectomy, meaning the findings may not apply to all women considering HRT today.
Implications for Women's Health
Dr Richard Oakley, associate director of research and innovation at Alzheimer's Society, commented: "Around two-thirds of people living with Alzheimer's disease in the UK today are women, and while we still don't fully understand why they are more susceptible than men, it is thought that hormones may play a role."
He added that there are steps everyone can take today to reduce dementia risk, such as regular exercise, not smoking, and reducing alcohol consumption. Both experts agree that larger and more diverse studies are needed to determine whether hormone-based treatments could play a role in reducing dementia risk, but the study provides valuable clues about the biology underlying dementia and highlights the need for more research into women's brain health.
