Older women who use a specific form of hormone replacement therapy may be at a lower risk of exhibiting physical signs of Alzheimer’s disease within the brain, according to new research.
Those prescribed oestrogen-only HRT were also found to have a decreased likelihood of developing dementia.
In addition, patients undergoing the treatment were less prone to memory loss or experiencing functional decline, the study observed.
However, experts cautioned that the conclusions “cannot necessarily be applied to all women considering hormone replacement therapy today”, as oestrogen-only treatments are usually offered solely to women who have had a hysterectomy.
To conduct the study, published in Neurology, researchers from Stanford University in the US evaluated data from two major national databases tracking Alzheimer’s disease.
Using data from more than 20,000 women they found that use of this hormone therapy in later life was linked to “significantly lower odds of a clinical dementia diagnosis” – with women taking the treatment seeing a 39% reduced risk compared to non-users.
They also had a 33% “lower odds of symptoms of memory/functional decline”, the authors wrote.
Post-mortem data from 258 menopause hormone treatment users and 2,701 non-users found 35% lower odds of biological signs of Alzheimer’s disease in the brain, including plaque build up.
Commenting on the study, Dr Tom Blackmore, research programmes manager at Alzheimer’s Research UK, said: “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.
“While these findings are interesting, 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.
“It’s also important to note that women in this study reported using oestrogen-only hormone therapy at an average age of around 70, which differs substantially from how hormone replacement therapy is typically used today.
“This research also focused on oestrogen-only hormone therapy, which is typically prescribed to women who have had a hysterectomy.
“This means the findings cannot necessarily be applied to all women considering hormone replacement therapy today.
“These findings are not a reason for women to start or stop hormone replacement therapy with the aim of reducing dementia risk.
“Instead, the study provides valuable clues about the biology underlying dementia and highlights the need for more research into women’s brain health.
“Larger and more diverse studies will be needed to determine whether hormone-based treatments could play any role in reducing dementia risk.”
Dr Richard Oakley, associate director of research and innovation at Alzheimer’s Society, said: “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.
“There are steps that everyone can take today to reduce their risk of dementia such as regular exercise, not smoking and reducing alcohol consumption.”