Women who start common hormone therapy in their 50s may have 23% lower dementia risk

Women who start hormone replacement therapy (HRT) at a certain age may have a lower dementia risk, a new study suggests.

The study, published in Alzheimer’s & Dementia, analyzed UK Biobank data of 183,450 postmenopausal women averaging 60 years of age.

The U.K. researchers determined that HRT use was associated with about a 10% lower risk of all-cause dementia and a 16% lower risk of Alzheimer’s disease over a 13-year follow-up period.

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The association was strongest among women who started the therapy between the ages of 46 and 56. It was also high among those who had undergone surgical menopause.

Starting HRT after age 56 was not associated with reduced dementia risk.

Dr. Alexa Fiffick, a board-certified family medicine physician and founder of Concierge Medicine of Westlake in Cleveland, Ohio, noted that this was an observational study that can’t show cause and effect.

"So, it kind of stays where the data has been for a while — that in certain patients, we have no evidence that it really makes a difference," she told Fox News Digital.

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"And, for some patients, such as [those] who go through menopause a little bit younger, whether that's surgically or naturally, or if they have that APOE ε4 genotype that predisposes them to dementia, there may be some benefit."

The researchers also stated that since this was an observational study, it could not establish that HRT prevents dementia but only showed an association.

The study also did not assess any safety outcomes or adverse events related to HRT.

Women who use HRT may differ from non-users in other ways that affect dementia risk, such as their overall health, lifestyle or access to healthcare, the researchers noted.

Although researchers adjusted for many of these factors, some unmeasured differences could still factor into the lower dementia risk seen among HRT users.

The study also did not have detailed information on the types of hormone therapy, the way they were administered or the specific dosages women took.

Most of the people in the study were of European ancestry and tended to be better off financially, so the findings may not apply equally to people from other populations.

This study alone likely doesn't warrant seeking out HRT just for dementia prevention, Fiffick said.

"However, if you're having symptoms, if you feel not yourself, come in, talk to your doctor, have that conversation," she advised.

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There is some data linking menopausal symptoms, such as hot flashes and night sweats, with vascular changes in the brain, the doctor noted.

"So, we are very hopeful to see that treating those symptoms may prevent the vascular changes that lead to vascular dementia, but we just don't have that data right now," she said. 

"So, it's worth the conversation, it's worth bringing up, but I wouldn't go out of your way for just this purpose."

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HRT does carry some known risks and side effects, Fiffick noted.

For oral versions of estrogen, there may be an increased risk of blood clots. That risk does not appear to exist for transdermal options, such as patches, gels and creams.

Other types of HRT may impact breast activity, overall inflammation, cardiovascular markers and cardiometabolic markers, according to the doctor.

"So, it's not one size fits all, and it's really worth an extensive conversation."

The U.K. researchers plan to conduct randomized controlled trials to confirm that HRT reduces dementia risk. Future studies will include factors such as estrogen-only versus combined therapy, dosage amounts, administration route, treatment duration, age at the start of therapy, menopause type and potentially APOE genotype.

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"I think the more we have studies like this, the more we're going to propel forward the randomized controlled trials to really give women the data they deserve," Fiffick concluded.

"Women deserve to have information to use to make decisions about their bodies. So I'm excited to see the trends heading in that direction."