Hormone replacement therapy not linked to an increased risk of developing dementia, study finds

HRT is used to treat hot flashes, night sweats, insomnia and mood changes due to the disappearance of sex hormones called estrogen and progesterone when women approach menopause.

(CNN)Hormone replacement therapy (HRT) is, for the most part, not linked with an increased risk of developing dementia, according to a large study of women in the United Kingdom.

However, the study -- which published in the BMJ medical journal Wednesday -- did show a slightly increased risk of developing Alzheimer's disease, a specific form of dementia, among women who used estrogen-progestogen therapies for between five and nine years and for 10 years or longer. That translated into five and seven extra dementia cases, respectively, per 10,000 women.
"While the observational nature of the study means we can't be sure of knowing what causes what, I think the results here can still reassure us that these hormone therapies mostly aren't associated with increased risk of dementias," Kevin McConway, emeritus professor of applied statistics at The Open University in the UK, told the Science Media Centre in London. He wasn't involved in the research.
    "And where there is some evidence of an increased risk, the increase isn't very big at all," he said.
      Previous research into dementia and HRT has been inconsistent, the study noted. Lab studies and small trials have suggested a beneficial link between estrogen and age-related brain decline. However, a large trial of HRT, the Women's Health Initiative Memory Study, found an increased risk of developing dementia among users of estrogen-progestogen treatments, but these women were all elderly. And a Finnish study that published in 2019 flagged an increased risk of developing Alzheimer's disease among users of both estrogen-only and estrogen-progestogen treatments.
      Using UK medical records, the researchers involved in the new study identified 118,501 women age 55 and over who were diagnosed with dementia between 1998 and 2020. A control group consisted of 497,416 women matched by age and by the same medical practice, who had no records for dementia.
      Of the women with a dementia diagnosis, they found that 16,291 -- 14% -- had used HRT. The same percentage of women in the control group, or 68,726 of them, also used the treatment.

        Not definitive