There was worrying news this morning for the million women in the UK who currently take HRT to ease their menopausal symptoms, which can include anxiety, brain fog, hot flushes and insomnia.
A Danish study, published in the British Medical Journal (BMJ), suggested that there was a link between the use of hormone replacement therapy (HRT) and an increased risk of dementia. Scientists surveyed 61,000 women in Denmark with an average age of 70 and found those who had taken HRT were 24 per cent more likely to develop dementia or Alzheimer’s disease, compared to similarly aged women who hadn’t taken it.
The researchers, from the Danish Dementia Research Centre, also suggested that the longer HRT was taken the more likely the women were to develop dementia.
Has HRT been linked with dementia before?
This isn’t the first time a link between dementia and HRT has been suggested. But several subsequent studies have in fact found the opposite to be true – that hormonal treatment reduces the risk. In January this year, research from the University of East Anglia (UEA) and the University of Edinburgh, found that HRT is associated with better memory, cognitive function and larger brain volumes, in women who carry the APOE4 gene, which is a risk factor gene for Alzheimer’s.
The research team found that HRT was most protective when taken early after symptoms of the perimenopause (the 10 years leading up to the menopause) or menopause start. Professor Michael Hornberger, from UEA, who worked on the study said: “It’s too early to say for sure that HRT reduces dementia risk in women, but our results highlight the potential importance of HRT and personalised medicine in reducing Alzheimer’s risk.”
Meanwhile, his colleague Dr Rasha Saleh said the effects of HRT “would equate to a brain age that is several years younger”.
In the past few years, experts have been investigating brain health and the hormonal changes that take place during the menopause, after it was found that two thirds of Alzheimer’s patients are women. These include the American neuroscientist Lisa Mosconi. In her TED Talk, How Menopause Affects The Brain, she suggests that oestrogen shields the brain, which starts ageing faster during the menopause if HRT isn’t taken.
So how are we to interpret this study?
Dr Richard Oakley is associate director of research and innovation at Alzheimer’s Society, “This latest study does not prove that HRT causes dementia,” he says. “The link it found could be down to other factors. For example, women who get help for their menopause symptoms may be more likely to approach their GP for other problems, such as dementia symptoms, later on.
“This research is highlighting an incredibly important topic in dementia but it’s clear that more research is needed to understand any potential links between HRT and dementia as current studies have conflicting results.”
Even the researchers themselves said their study shouldn’t be used “to infer a casual relationship between hormonal therapy and dementia risk”. Lead author, Dr Nelsan Pourhadi, said more research is needed and that women should continue to take HRT in the meantime.
“It was also an observational study, so it doesn’t prove cause and effect,” says menopause expert Dr Shahzadi Harper, author of The Perimenopause Solution. “The study participants were also older, with an average age of 70, when dementia is slightly more likely anyway.”
And as Dr Oakley points out, the researchers didn’t distinguish why HRT was prescribed in the first place. For example, whether it was to treat existing changes in sleep or memory, which can be early symptoms of dementia.
Dr Sarah-Naomi James of the MRC Unit for Lifelong Health and Ageing at University College London, issued a statement after the study was published that said, “This new study alone should not change practice.” She also said the study had “fundamental limitations” in how it linked HRT and dementia, when the reasons for prescribing HRT in the first place, such as brain fog, memory problems and insomnia, are similar to the early symptoms of dementia.
Should you continue to take HRT?
“We know that when women start HRT in the window of opportunity that starts within 10 years of menopause it often comes with more benefits to their quality of life than not,” says Dr Harper. “And this can improve and protect their health in various ways.
“For example, HRT for a woman who was previously experiencing hot flushes, night sweats, insomnia or anxiety, can lead to behavioural changes that improve her overall health, such as getting a good night’s sleep, making smart food choices, and exercising regularly. Every menopausal woman knows she should be doing those things, but if her hormones are having an impact on her energy, mood and motivation, then she may not be, which can be detrimental to her health.”
Sleep is another area Dr Harper says HRT can help with. A 2021 study from University College London found that women who sleep fewer than six hours a night in their 50s and 60s were more likely to develop dementia in later life.
“If HRT helps you sleep better – and many studies have shown a benefit of HRT on sleep – then you’re protecting your brain health,” says Dr Harper. “Sleep has also been linked to weight management, which reduces your risk of things like heart disease.
“These studies can be very scaremongering for women on HRT. But I think they need to be taken with a pinch of salt.”