A new international study led by the University of Galway is shedding light on the complex relationship between women's hormones, menopause and the ageing brain. Speaking on Drivetime, Professor Emer McGrath — Associate Professor of Medicine at the University of Galway and Consultant Neurologist at UHG — explained how her team has uncovered intriguing links between reproductive history, hormone replacement therapy (HRT) and dementia risk.

The Galway researchers analysed data from over 1,300 women who were part of the famous Framingham Heart Study — a long-running US project that began back in the 1940s, as Prof. McGrath explains:

"It was started back in President Roosevelt’s time when they wanted to look at why Americans were having such high deaths from heart disease. We looked at individual women in that study who have provided data on MRI scans, cognitive testing and who have been followed forward for decades now in terms of dementia risk."

This detailed dataset allowed Prof. McGrath and her team in Galway to explore how reproductive factors — such as age at menopause and number of pregnancies — might relate to cognitive health and brain structure later in life:

"It was an observational cohort study. We related different risk factors — reproductive factors in this particular case — and then looked at their MRI scans, cognitive test performance; so things like testing thinking and memory and dementia."

One of the study’s main findings was that women who experience menopause earlier may face a higher risk of developing dementia. Prof. McGrath says there may be something there, but further study is needed to confirm the findings:

"It’s an association that we found, but I’ll qualify it — the sample size is not enormous. I think it’s very interesting. There have been studies to date that have looked at this and there have been conflicting findings."

The Galway team believes the timing of hormonal changes may be a crucial piece of the puzzle:

"There may be a ‘critical window of opportunity’ around the time of menopause when the use of hormone replacement might be more beneficial. This would really set the platform for a clinical trial looking at HRT and women around the time of menopause — starting early on — to see if it can have cognitive benefits later on in life and really help with healthy brain ageing."

Perhaps the most striking finding was that HRT after menopause appeared to be linked with a lower risk of dementia, Prof. McGrath explains:

"We found that higher blood-oestrogen levels, or if you were older when you entered the menopause, or if you’ve used HRT after menopause — those women tended to have better cognitive performance on tests of memory and thinking".

However, Prof. McGrath emphasised that the results show a correlation rather than proof of cause and effect and the findings need to be replicated in future studies before drawing solid conclusions. Still, the results have opened up exciting new avenues for research, which may help refine and improve treatments over time:

"You’re trying to reach that sweet spot, where you’re giving, potentially, HRT at the right time to really help women improve their symptoms of the menopause, and potentially improve cognition. But at the same time, you need to be cognisant of their risk of heart disease and stroke and clotting, which is one of the downstream effects."

Beyond HRT, another finding surprised even the researchers themselves: women who had more children tended to have better cognitive test results, particularly in visual-spatial skills:

"Women who have more children were found to have larger brain volumes on MRI scans, and that was even in the areas where we tend to see shrinkage in Alzheimer’s disease. When we also looked at these women who had more children, we found that they had better visual-spatial skills — which was very interesting."

While the findings are still preliminary, the study highlights how women's hormonal health is deeply linked to brain health — and why future clinical trials are needed, says Prof. McGrath:

"It’s an area ripe for exploration. If we can better understand how hormones affect the brain, we can help women age more healthily, both in body and mind."

For women listening to the conversation on Drivetime who may have entered menopause early, Prof. McGrath offered reassurance:

"We may have seen an effect here where early menopause is associated with an increased dementia risk, but there’s a huge amount women can do to reduce their risk of dementia."

That advice, she noted, is timeless:

"It goes back to that timeless message we all know: healthy lifestyle, regular exercise, eating well, taking good control of your health, making sure you are monitoring your blood pressure and being involved with large social networks, which are associated with reduced risk of brain ageing."