Does Menopausal Hormone Therapy Lower Dementia Risk? Timing And Genetics May Hold The Answer

• A longer reproductive life span, particularly later menopause, was associated with fewer signs of small-vessel disease in the brain, including approximately 8% lower odds of having multiple disease markers.
• Menopausal hormone therapy (MHT) was associated with fewer signs of small-vessel disease and better white matter integrity, although these associations may vary depending on genetic and individual health factors.
• While MHT may offer potential brain health benefits when started around menopause, it has not been proven to prevent Alzheimer’s disease or dementia.

Women who have longer reproductive life spans or use menopausal hormone therapy (MHT) may have better brain health as they age, according to a new study.

The research, published November 4 in Neurology, found that longer lifetime exposure to estrogen was associated with fewer signs of damage to small blood vessels in the brain.

The findings could offer new insights into the relationship between estrogen and brain aging, particularly as women account for approximately two-thirds of Alzheimer’s disease cases worldwide.

Researchers also found that certain associations between hormone therapy and brain health differed depending on whether women carried a genetic variant associated with an increased risk of Alzheimer’s disease.

However, the relationship between estrogen and brain health is complex. While the findings suggest that longer estrogen exposure may be associated with healthier brain aging, they do not establish that hormone therapy can prevent Alzheimer’s disease or dementia.

Longer estrogen exposure linked to better brain blood vessel health

The researchers drew data from the Gothenburg H70-1944 Birth Cohort, a longitudinal study of 1,203 individuals born in 1944 who resided in Gothenburg, Sweden. 

The final cohort included 352 cisgender women, with an average age of 70, who had no neurological disorders and reliable self-reported data on their estrogen exposure. 

Individual estrogen exposure was measured through structured interviews. It included: 

• age of first menstruation
• age of menopause
• type of menopause (surgical or natural)
• use of oral contraceptives
• use of MHT

The researchers used this information as a proxy for lifetime estrogen exposure, though the study didn’t measure actual hormone levels. 

Participants were also given a brain MRI at baseline and then again at a 5-year follow-up. 

The researchers found that those with a longer reproductive span had a lower risk of small vessel disease (SVD). Participants with a longer reproductive life span had an 8% lower risk of having two or more signs of SVD. However, later menopause, rather than earlier menstruation, appeared to be the main driver of this association.

Those who used MHT also tended to have fewer signs of SVD and better microstructural integrity in the white matter. 

In individuals who carried the APOE-ε4 variant, which increases a person’s risk of Alzheimer’s disease, MHT was associated with greater cortical thickness in brain regions vulnerable to Alzheimer’s disease. However, there was no association for those without this variant. 

The researchers noted that longer estrogen exposure was associated with stable cortical thickness and white matter trajectories over time. 

Dung Trinh, MD, internist at MemorialCare Medical Group and Chief Medical Officer of Healthy Brain Clinic in Irvine, CA, who wasn’t involved in the study, told Healthline that estrogen has several important effects on the brain that may help support cognitive health. 

It influences communication between brain cells, supports the brain’s ability to use glucose for energy, helps regulate neurotransmitters, and plays a role in maintaining healthy blood vessels and reducing inflammation and oxidative stress.

“As estrogen levels decline during menopause, some of these protective effects may diminish. Replacing estrogen closer to the menopause transition could potentially help preserve some of these functions during a vulnerable period for brain health,” he said. “While these findings are encouraging, MHT has not been proven to prevent Alzheimer’s disease or dementia.” 

Sherry Ross, MD, board certified OB/GYN and Women’s Health Expert at Providence Saint John’s Health Center in Santa Monica, CA, who also wasn’t involved in the study, agreed and noted, “Starting menopausal hormone therapy earlier in the menopause transition may help minimize some changes by supporting the brain during this period of hormonal fluctuation.”

“There is growing interest in whether early estrogen therapy may also help reduce the long-term risk of Alzheimer’s disease, although more research is needed before we can establish that benefit,” she added. 

Why menopause hormone therapy should be individualized

Ross told Healthline that this research reinforces the importance of recognizing menopause as more than a reproductive or hormonal transition.

“We know that women are disproportionately affected by dementia and Alzheimer’s disease, and some women experience noticeable cognitive changes beginning in perimenopause,” she said.  “If future research confirms that starting hormone therapy earlier can help protect long-term cognitive health, it could influence how we approach menopause treatment and encourage more proactive conversations between women and their healthcare providers.” 

“The goal should be to individualize treatment based on a woman’s symptoms, medical history, and overall health rather than taking a one-size-fits-all approach,” Ross added. 

Trinh agreed that an individualized approach to menopause management is important. 

“This does not mean that every woman should start hormone therapy to prevent dementia. Instead, it highlights the importance of understanding which women might benefit, when treatment should begin, and which formulations are most appropriate,” he said. “Factors such as age, time since menopause, cardiovascular risk, metabolic health, family history, and potentially genetic factors may all help guide future recommendations.” 

“We still need stronger clinical evidence before changing current prescribing guidelines specifically for dementia prevention,” Trinh added.