Could HRT reduce dementia risk? What a new UK study really found.

At 51, I’m definitely more interested in what’s happening inside my body than whether another wrinkle has appeared on my face. Perimenopause has so far given me interrupted sleep, questionable concentration and the inability to remember why I’ve walked into a room. So when I read about new research linking HRT with a lower risk of dementia, I wanted to know what the scientists had discovered.

The findings are encouraging for certain groups of women. But understanding what the researchers measured matters just as much as the numbers themselves.

What did the HRT and dementia study find?

Researchers from the University of East Anglia and the University of Exeter analysed health information from 183,450 postmenopausal women participating in the UK Biobank. The women were followed for an average of 13.3 years, during which almost 4,000 dementia cases were recorded. The researchers reported that HRT use was associated with approximately a 10% lower observed risk of dementia overall and a 16% lower risk of Alzheimer’s disease. Among women who had experienced surgical menopause, the association was stronger, with a 26% lower observed dementia risk.

There were other interesting findings. Women with lower lifetime exposure to oestrogen appeared to experience a greater reduction in risk. The association was also stronger among women carrying APOE4, a genetic variant linked to an increased likelihood of developing Alzheimer’s disease. Those figures certainly caught my attention. However, before anyone starts treating their HRT prescription as insurance against dementia, there’s an important distinction to understand.

Does HRT prevent dementia?

This was an observational study, meaning researchers examined existing health information rather than randomly assigning women to receive HRT. They identified associations, but couldn’t establish whether the treatment itself was responsible for the differences. Women who take HRT may differ from those who don’t in ways that influence their long-term health. Medical history, lifestyle and access to healthcare can all complicate the picture. That doesn’t make the findings meaningless. It just means we shouldn’t turn an encouraging association into a medical promise.

Why does menopause affect memory and concentration?

Oestrogen does more than regulate our reproductive systems, its receptors are found throughout the body, including in the brain, and changing hormone levels during menopause can affect sleep, mood, concentration and memory. I’ve experienced enough brain fog to appreciate how frustrating those changes can be. Some mornings, my brain is capable of remembering an obscure conversation from 1998 but struggles with what I intended to do five minutes ago.

However, menopause-related brain fog is not the same as dementia. Forgetting why you’ve entered the kitchen isn’t evidence of a neurodegenerative condition. When dementia has affected your family, though, it’s understandable that memory lapses can feel unsettling. And this is particularly when alarming health headlines have a habit of making ordinary symptoms sound more sinister than they are.

Does the age you start HRT make a difference?

One finding concerned treatment timing. Women who started HRT between 46 and 56 showed the greatest reduction in observed dementia risk. This relates to what’s known as the critical window hypothesis, which suggests hormone therapy may have different effects depending on when treatment starts in relation to menopause. It’s an interesting theory for women considering treatment during perimenopause, although more research is needed to establish its significance.

The findings concerning surgical menopause also deserve attention. Removing the ovaries can cause an abrupt reduction in hormone levels, unlike the more gradual transition experienced during natural menopause. A woman whose ovaries are removed at 42 may face different health considerations from someone who reaches menopause naturally at 51. Understanding these differences could help healthcare professionals make more individualised treatment decisions.

What does this mean for women in midlife?

For years, menopause has been discussed largely in terms of surviving symptoms. Manage the hot flushes, endure the sleepless nights and try not to lose your temper when somebody asks why you’re tired. I’m increasingly interested in what happens afterwards. I exercise because I want to maintain muscle and independence. I’d like to keep enjoying the gym and managing my own affairs without needing assistance to lift a suitcase. I don’t expect to feel 30 again, although I wouldn’t object to having the energy I had then.

But physical fitness is only part of the picture. Cardiovascular health, bone density and mental wellbeing deserve attention too. Menopause isn’t just an inconvenient collection of symptoms. It’s a biological transition with implications researchers are still working to understand. And while we’re encouraged to worry about our waistlines, wrinkles and whether we’re eating enough protein, I’d argue that understanding the longer-term effects of hormonal changes is more useful than another lecture about ageing gracefully.

Should women take HRT to prevent dementia?

Current evidence doesn’t justify prescribing HRT specifically to prevent dementia. Treatment decisions should consider menopausal symptoms, medical history, individual risks and potential benefits, ideally through a conversation with a qualified healthcare professional. For women already taking HRT, these findings provide an interesting subject for discussion, not a reason to change treatment independently.

Personally, I’d welcome more research into how menopause affects women’s health decades after our periods have stopped. We spend so much of our lives discussing fertility and reproduction, yet the years that follow deserve equally serious scientific attention.

About the research

The study, Hormone replacement therapy and dementia risk among postmenopausal women: identifying responsive subgroups in the UK Biobank, was conducted by researchers at the University of East Anglia and the University of Exeter and published in Alzheimer’s & Dementia.

This article discusses published research and personal experiences of midlife wellbeing. It is not medical advice. Speak to your GP or a qualified healthcare professional about treatment decisions.

Occasional stories, experiments, discoveries and questions from Saffron & Cyrus.