Women who begin hormone replacement therapy (HRT) during a specific timeframe in midlife may lower their risk of developing dementia in later years, according to major new research.
A team led by the University of East Anglia and the University of Exeter examined medical data from more than 183,000 post-menopausal participants enrolled in the UK Biobank project.
Over an average follow-up period of 13 years, nearly 4,000 of these women received a dementia diagnosis.
Researchers discovered that taking hormone therapy was linked to a 10 per cent lower risk of overall dementia and a 16 per cent reduction in Alzheimer’s disease specifically.
Commencing treatment between the ages of 46 and 56 offered the greatest benefit.
They found that those who started HRT aged 46 to 50 had a 13 per cent reduced risk of dementia, while those who started taking HRT when they were aged 51 to 56 saw a 23 per cent reduced risk.
Meanwhile those who carry the gene variant APOE4 – a risk factor for Alzheimer’s – who also took HRT, had a 13 per cent reduced risk of dementia.
And stronger links were found with women who took HRT after surgical menopause; these women had a 26 per cent lower risk of being diagnosed with dementia.
The study also found that women who naturally had lower exposure to oestrogen over their lifetime, due to starting their periods late or early menopause, seemed to have a 16 per cent reduced odds of dementia after taking HRT.
“HRT use was associated with lower dementia risk, and these findings may help inform more tailored approached to HRT prescribing in relation to women’s lifetime dementia risk, the authors wrote in the journal Alzheimer’s and Dementia.
Study lead, Professor Anne-Marie Minihane, director of the Norwich Institute for Healthy Aging at UEA, said: “We found that women who had used HRT were about 10 per cent less likely to develop dementia, and 16 per cent less likely to develop the Alzheimer’s disease form of dementia, than women who had never used it.
“But the protective association between HRT and dementia was not the same for all women.”
She added: “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.”
Prof David Llewellyn, from the University of Exeter Medical School, added: “These findings represent a significant step forward.
“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.”
Dr Amanda Collis, executive director for Research Strategy and Programmes at the Biotechnology and Biological Sciences Research Council, which funded the study, said: “This study provides valuable new insights into how menopause and the timing of hormone replacement therapy may influence dementia risk in women.
“The findings suggest that HRT could have greater protective benefits for some groups, highlighting the potential for more personalised approaches to prevention.”
Commenting on the study, Aimee Spector, professor of clinical psychology of ageing and the director of the Menopause Mind Lab at University College London (UCL), said: “The results are promising in that they analysed data from the UK Biobank using large samples.
“The novelty of their findings was timing of HRT initiation, with those who started HRT between the ages of 46-56 conferring the greatest benefit.
“This supports the ‘window of opportunity’ hypothesis, suggesting that HRT use during the menopause transition phase, where symptoms are typically more problematic; is important.”
