An Australian expert has downplayed concerns from the largest study to date suggesting long-term use of hormone replacement therapy increases a woman’s risk of developing Alzheimer’s disease.
The Finnish cohort study looked at more than 80,000 postmenopausal women diagnosed with Alzheimer’s disease, matched with controls, over a 15-year period.
They found that women with Alzheimer’s disease had used systemic HRT slightly more often than those without the disease, 18.6% vs 17%.
In absolute terms, this meant that 9-18 additional cases of Alzheimer’s disease per 10,000 women per year would be detected in women 70-80 years of age.
While the absolute risk was small, women should still be informed, the authors said.
“Our data should be implemented into information for present and future users of hormone therapy,” they said.
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The greatest risk was for women who had used oestrogen-progestogen combination HRT for more than 10 years.
In Finland, 90% of hormone therapy is oral.
In a linked editorial, epidemiologist Dr JoAnn Manson, of Harvard Medical School, and psychiatrist Dr Pauline Maki, of the University of Illinois in Chicago, say the findings should not warrant any changes to clinical decision-making about short term HRT for women with bad menopause symptoms.
“For women in early menopause with bothersome vasomotor symptoms, no compelling evidence exists of cognitive concern from randomised trials and instead there is reassurance about cognitive safety,” they say, adding that concerns remain over longer-term use of estrogen-progestogen on cognition.
Endocrinologist Dr Sonia Davison, of Jean Hailes for Women’s Health in Melbourne, said women and GPs could take comfort in the fact that in absolute terms the risk was low.
“This is very reassuring,” the Australasian Menopause Society president-elect said.
“Certainly, it shouldn’t put a woman off HRT if she’s having bothersome symptoms around the time of menopause; all the societies agree that the benefit of HRT in that group far outweighs the risks.”
Dr Davison said the study had some important limitations, including a failure to account for the fact that a high proportion of the Finnish population, almost 20%, carry the ApoE E4 allele that is strongly linked to Alzheimer’s.
More information: BMJ 2019