Hormone Therapy for Breast Cancer May Decrease Dementia Risk

A new study indicates that hormone therapy for breast cancer may lower a woman's risk of developing dementia and Alzheimer's disease in the future. Published on July 16 in the journal JAMA Network Open, the study found that hormone therapy is generally associated with a 7% reduced risk of Alzheimer's and related dementias later in life. However, the association varies with age and race.

“These results highlight the need to consider individual patient factors when prescribing medications or creating treatment plans for breast cancer,” said senior researcher Francesmary Modugno, a professor at the University of Pittsburgh. “There is no one-size-fits-all approach; personalized treatment is crucial for optimizing outcomes and minimizing risks.”

Approximately two-thirds of breast cancer patients have tumors driven by the female hormones estrogen or progesterone. Hormone therapy can slow tumor growth in these patients by blocking these hormones. The study examined data from over 18,800 women aged 65 and older who were diagnosed with breast cancer between 2007 and 2009. Researchers found that 66% of these women received hormone therapy within three years of their diagnosis.

Over an average follow-up period of 12 years, 24% of the women who underwent hormone therapy developed Alzheimer's or dementia, compared to 28% of those who did not receive hormone therapy during their cancer treatment. The protective effect of hormone therapy was most significant in women aged 65 to 69 but was not observed in women over 80, where it actually increased the risk of dementia.

Race also influenced the outcomes. Black women aged 65 to 74 using hormone therapy had a 24% reduced risk of dementia, which slightly decreased to a 19% reduction after age 75. White women aged 65 to 74 experienced an 11% reduction in dementia risk with hormone therapy, but this benefit disappeared after age 75.

“Our research suggests that younger women may gain more cognitive benefits from hormone therapy, particularly in terms of reduced Alzheimer's disease and dementia risk,” said lead researcher Chao Cai, an assistant professor at the University of South Carolina College of Pharmacy. “The benefits diminish for women aged 75 and older, especially among white women. This underscores the importance of considering the timing of hormone therapy and tailoring treatment plans according to a patient's age.”

Cai added that estrogen appears to protect brain health, and hormone therapy might influence dementia risk by affecting estrogen or brain receptors responsive to the hormone. It could also impact proteins like amyloid beta and tau, which are associated with Alzheimer's, or the health of small blood vessels in the brain.