Breast Cancer Survivors May Face Lower Risk of Alzheimer’s, Study Finds

A new study suggests that breast cancer survivors may be less likely to develop Alzheimer’s disease than women who have never had cancer, particularly in the first five years after diagnosis. The findings, published in JAMA Network Open, add to growing evidence that cancer and Alzheimer’s disease may stem from distinct biological pathways. 

Heather Jim, PhD

Researchers in South Korea analyzed national health records from more than 70,000 women who had breast cancer surgery between 2010 and 2016, comparing them with over 212,000 cancer-free women. After a median follow-up of 7.3 years, breast cancer survivors showed an 8% lower risk of developing Alzheimer’s dementia. The protective effect was strongest in women age 65 and older and in those who received chemotherapy and radiation. 

“The findings are consistent with previous studies suggesting that cancer and its treatment is often associated with a lower risk of Alzheimer’s disease,” said Heather Jim, PhD, associate center director of Population Science at Moffitt Cancer Center. “An exception is prostate cancer treated with androgen deprivation therapy.” 

Could Cancer Treatment Offer Brain Benefits? 

One possible explanation for the lower Alzheimer’s risk may lie in clonal hematopoiesis, a condition in which blood stem cells acquire mutations as people age. These mutations have been linked to increased cancer risk but lower risk of Alzheimer’s. 

Nancy Gillis, PhD

“Cancer treatment can lead to expansion of clonal hematopoiesis mutations,” said Nancy Gillis, PhD, a molecular epidemiologist in the Cancer Epidemiology Department at Moffitt. “Perhaps this cancer treatment-related clonal hematopoiesis expansion contributes to the decreased risk of Alzheimer’s seen in patients with breast cancer.” 

Gillis said her team is seeing similar trends in an ongoing study at Moffitt. 

Chemo Brain and Alzheimer’s: Not the Same  

Still, many breast cancer survivors report memory issues, brain fog and trouble focusing after treatment, commonly called “chemo brain.” But researchers stress that these symptoms differ from Alzheimer’s disease. 

“Cancer-related cognitive impairment seems to be distinct from Alzheimer’s,” Jim said. “Survivors often need more mental effort to complete the same tasks, which is why they may feel mentally foggy, especially when tired or distracted. Alzheimer’s, in contrast, is driven by ongoing neurodegeneration.” 

Gillis echoed that distinction. 

“These findings, along with Dr. Jim’s work, point to the fact that cancer-related cognitive impairment and Alzheimer’s arise from different mechanisms,” she said. “They also suggest that cancer therapy may even offer a protective benefit against Alzheimer’s disease.” 

Breast cancer survivors may have a slightly lower risk of Alzheimer dementia compared with cancer-free individuals, potentially related to cancer treatments. https://t.co/pWNcD9T5TY pic.twitter.com/fYRQQ9GkeL

— JAMA Network Open (@JAMANetworkOpen) June 20, 2025

More Questions Ahead 

The study has limitations. It’s observational, based in Korea and lacks details on tumor biology or family history. Experts still believe it’s an important step in better understanding how cancer and brain aging intersect. 

“The magnitude of risk reduction is modest, and more research is needed,” Jim said. “But these results help lay the groundwork for future studies on how cancer and its treatment may affect long-term brain health.”