Women who take HRT have lower risk of Alzheimer’s
MELBOURNE: Women who take hormone replacement therapy to ease menopause symptoms are 16 per cent less likely to get Alzheimer’s disease, a study has found.
A team at the University of East Anglia followed 183,000 postmenopausal women in the UK for 13 years, and found rates of dementia were significantly lower among those on HRT.
The effect was strongest when HRT was started between the ages of 46 and 55. Experts said this period was a critical “window of opportunity” to get the most benefits and protect the brain.
HRT is taken by 2.8 million women in England and is given as pills, patches or gels. It provides oestrogen to replace falling hormone levels during the menopause, which starts on average at the age of 51.
HRT is the first-line treatment on the UK National Health Service for symptoms such as hot flushes and night sweats.
Women are twice as likely to develop dementia as men, and research suggests this is partly due to hormonal changes during the menopause that cause a loss of brain tissue.
The study, the largest of its kind, used data from the UK Biobank to examine whether HRT could mitigate this and protect the brain. Overall, women were 10 per cent less likely to get any type of dementia if they used HRT, compared with those who had not. They were 16 per cent less likely to get Alzheimer’s disease, the most common type.
Starting HRT soon after symptoms began was most beneficial and those who started taking it aged 51 to 56 had a 23 per cent reduced risk.
Professor Anne-Marie Minihane, leader of the study and director of the Norwich Institute of Healthy Ageing at the university, said: “We found that HRT is especially beneficial for women who have gone through a surgical menopause, for example after having their ovaries removed. In this group, those who used HRT were around 26 per cent less likely to develop dementia.”
The research also found HRT had greater benefits in cutting dementia in women with the APOE4 gene variant, which raises the risk of Alzheimer’s.
Professor David Llewellyn of the University of Exeter, a co-author, said: “Rather than asking simply whether HRT affects dementia risk, we’ve been able to identify which women are most likely to benefit, and when.”
The study is observational, which means it cannot prove cause and effect. The benefits of HRT must also be balanced against risks, including a higher chance of developing breast cancer.
Dr Susan Kohlhaas, the executive director of research and partnerships at Alzheimer’s Research UK, said: “Women are more likely than men to develop dementia, but we don’t fully understand why. Hormonal changes around the menopause could be part of the picture, making the relationship between HRT and dementia risk an important question to understand.
“As an observational study, this research cannot establish that HRT itself lowered dementia risk. Women who use HRT may differ from women who don’t in other ways that affect their risk of dementia.
“This study alone isn’t enough to tell us whether HRT should be used to reduce dementia risk, but it provides further evidence that the timing of HRT and a woman’s hormonal history may matter. We now need research that can establish whether HRT itself is responsible for these differences in dementia risk and understand which forms of HRT may have an effect.”
Professor Aimee Spector, the director of the Menopause Mind Lab at University College London, 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 and 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.”
The study was published in the journal Alzheimer’s and Dementia.