• Posted July 16, 2024

Hormone Therapy for Breast Cancer May Lower Dementia Risk

Hormone therapy for breast cancer might reduce a woman's later risk of dementia and Alzheimer's disease, a new study finds.

Overall, hormone therapy is associated with a 7% lower risk of developing Alzheimer's or a related dementia later in life, according to findings published July 16 in the journal JAMA Network Open.

However, this link decreases with age and varies by race, results showed.

"Our findings emphasize the importance of being cognizant of individual patient factors when we prescribe medications or develop treatment plans for breast cancer,"said senior researcher Francesmary Modugno, a professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh.

"It's not one-size-fits-all,"Modugno added in a university news release. "We need to think about each individual patient to optimize outcomes and minimize risks."

About two-thirds of breast cancer patients have a tumor that is fueled by the female hormones estrogen or progesterone. Hormone therapy in those patients can impede tumor growth by blocking those hormones.

For this study, researchers analyzed data on more than 18,800 women aged 65 and older who'd been diagnosed with breast cancer between 2007 and 2009.

Two-thirds of the women (66%) had received hormone therapy within three years of their diagnosis, researchers found.

During an average 12-year follow up, 24% of hormone therapy patients developed Alzheimer's or dementia, compared with 28% of women who didn't use the drugs during cancer treatment, results show.

The protective effect was strongest in women ages 65 through 69, researchers said. On the other hand, hormone therapy actually increased dementia risk in women older than 80.

Race also appeared to play a role in risk.

Black women ages 65 to 74 using hormone therapy had a 24% reduction in risk for dementia, and that only dropped to a 19% lower risk after age 75, results show.

White women ages 65 to 74 had an 11% risk reduction for dementia tied to hormone therapy use, but that beneficial association disappeared after 75.

"Our study suggests that younger women may benefit more from [hormone therapy] in terms of reduced risk of developing Alzheimer's disease and other types of dementia,"said lead researcher Chao Cai, an assistant professor with the University of South Carolina College of Pharmacy.

 "The benefits of [hormone therapy] decreased for women aged 75 and older, particularly in those who identified as white. This suggests that the timing of [hormone therapy] initiation is crucial and treatment plans should be tailored to a patient's age,"Cai added.

Estrogen tends to protect brain health, Cai said. These drugs could influence dementia risk by manipulating either estrogen or brain receptors that respond to the hormone, she speculated.

It also could be that hormone therapy affects proteins like amyloid beta and tau that are closely linked to Alzheimer's risk, or the health of small blood vessels that feed the brain, researchers added.

"The relationship between [hormone therapy] for breast cancer and dementia risk is complex and influenced by multiple factors,"Cai said. "Ongoing research is needed to further understand the mechanisms behind this association and provide clearer guidance on the use of [hormone therapy]."

More information

The American Cancer Society has more on hormone therapy for breast cancer.

SOURCE: University of Pittsburgh, news release, July 16, 2024