Many women take hormone replacement therapy (HRT) to ease hot flushes, night sweats and other menopause symptoms. But could it also protect your brain years down the track?
New research published in the journal Alzheimer’s & Dementia suggests taking HRT in midlife could help protect against dementia.
Researchers also identified a ‘window of opportunity’, with women who started treatment at certain ages seeing the biggest drop in risk.
In Australia, around 80,000 women enter menopause each year. Women also make up nearly two-thirds of the almost half a million Australians currently living with dementia.
Living longer is part of the reason women are more likely to develop dementia, but researchers believe the hormonal changes that happen during menopause may also play a role.
What did the study find?
In the largest study of its kind, researchers from the University of East Anglia and the University of Exeter analysed health data from more than 183,000 postmenopausal women in the UK. Over an average of 13 years, almost 4000 were diagnosed with dementia.
Women who had used HRT for at least one year were 10 per cent less likely to develop any type of dementia than women who had never used it. Their risk of Alzheimer’s disease, the most common form of dementia, was 16 per cent lower.
“While HRT has long been prescribed primarily to relieve menopausal symptoms such as hot flushes and night sweats, this work suggests it may also play a role in long-term cognitive health for some women,” says study lead Professor Anne-Marie Minihane, director of the Norwich Institute for Healthy Ageing at the University of East Anglia.
“But the protective association between HRT and dementia was not the same for all women,” Professor Minihane adds.
The greatest reduction was among women who had undergone surgical menopause, which happens when both ovaries are removed. Those who used HRT had a 26 per cent lower risk of dementia.
Women who had less exposure to oestrogen over their lifetime – because they started their periods later or reached menopause earlier – had a 16 per cent lower risk if they used HRT.
Those who carried the APOE4 gene variant, a known risk factor for Alzheimer’s disease, also had a 13 per cent lower risk if they used HRT.
“This is really important because APOE4 carriers are typically considered at higher risk and have fewer established prevention options,” says Professor Minihane.
Does it matter when you start HRT?
The researchers also broke down the results by how old women were when they started HRT.
Women who began taking HRT between the ages of 46 and 50 had a 13 per cent lower risk of dementia than those who had never used it. For women who started between 51 and 56, the risk was 23 per cent lower.
The same result wasn’t seen in women who began HRT after 56.
This supports what’s known as the “window of opportunity” theory, which suggests HRT may have the greatest benefits for the brain when started during perimenopause or soon after menopause.
“These findings represent a significant step forward,” says Professor David Llewellyn from the University of Exeter Medical School.
“Rather than asking simply whether HRT affects dementia risk, we’ve been able to identify which women are most likely to benefit, and when.
“That’s the foundation on which genuinely personalised approaches to women’s brain health can be built.”
The researchers stressed that because the study was observational, it can’t prove HRT was responsible for the lower risk. HRT is not currently recommended solely to prevent dementia.
If you’re considering starting or stopping HRT, speak to your GP about whether it’s right for you.
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