Menopausal hormone therapy not linked to dementia onset

Menopausal hormone therapy (MHT — also known as hormone replacement therapy, HRT) does not appear to increase the risk of dementia onset, researchers reported on Sept. 29, 2021 in the BMJ/British Medical Journal.

“We are happy to be able to report findings that will reassure women needing menopausal hormone therapy and facilitate conversations between doctors and patients about the safest treatments,” said lead investigator Dr Yana Vinogradova from the School of Medicine at the University of Nottingham (UK).

For this new analysis, investigators used data from two of the largest primary care databases in the UK (QResearch and CPRD), which contain records of diagnoses and prescriptions as well as hospital records. This information made it possible for the researchers to evaluate dementia outcomes among subjects using MHT within the UK National Health Service over a long period.

The analysis included 118,501 general population subjects aged 55 and older diagnosed with dementia between 1998 and 2020, and 497,416 matched “control” subjects who had not been diagnosed with dementia during the same period.

MHT prescriptions gathered from over three years before a dementia diagnosis included details of hormone type, dose, and method of administration.

They reported that 16,291 (14%) of the MHT-treated subjects developed dementia in the study period, and 68,726 (14%) MHT-treated controls also developed dementia in the study period.

Notably, they reported a non-significant increased risk of Alzheimer’s disease onset among subjects who had used oestrogen-progestogen therapy for between five and nine years and for 10 years or more.

The authors concluded, “This large observational study found no overall association between use of menopausal hormone therapy and risk of developing dementia. This finding was consistent across different types of hormones, doses, applications, and time of hormone therapy initiation. We found a decreased risk dementia for cases and controls younger than 80 years at diagnosis who had been taking oestrogen-only therapy for 10 years or more. However, a subgroup analysis of cases with a diagnosis of Alzheimer’s disease showed a small increase in risk associated with oestrogen-progestogen therapy. This rose with each year of exposure, reaching average risk increase of 11% for between five and nine years of use and 19% for 10 years or more—equivalent to, respectively, five and seven extra cases per 10 000 woman years.”

They also noted that the results are, “in line with existing concerns in guidelines about long term exposures to combined hormone therapy treatments.”