Cognitive issues are a common side effect of cancer treatment. Often known as chemo brain, these issues can include trouble concentrating, remembering things, or learning new things. It’s estimated that up to 75% of cancer patients experience this during treatment, and about a third will continue to do so after treatment has ended. What does this mean for the risk of diseases impacting cognitive health, though? A new study aimed to answer that question.

Research recently published in JAMA Network Open investigated whether breast cancer patients were more likely to develop Alzheimer’s disease. To determine this, the team analyzed Korean National Health Insurance Service data on more than 70,000 breast cancer survivors, who were matched 1 to 3 with data from cancer-free peers. The findings showed that survivors had a lower risk of developing Alzheimer’s within five years of treatment, which suggests cancer-related cognitive difficulties won’t necessarily lead to more serious issues.

The study authors write, “The risk of [Alzheimer’s disease] is a crucial aspect of overall well-being among breast cancer survivors. Concerns about chemo brain and the long-term adverse effects of breast cancer treatment on cognition are common, but our findings suggest that this treatment does not directly lead to [Alzheimer’s disease].”

The survivors who took part in the study had all undergone breast cancer surgery between 2010 and 2016. They were followed for a median period of 7.3 years and were an average age of 53. The analysis was performed in 2024. By that time, 1,229 survivors had developed Alzheimer’s. However, they had an 8% lower risk than their cancer-free peers, and the benefit was especially pronounced if they were over 65. This apparent protective effect only lasted for five years, though.

The researchers believe the type of treatment may have something to do with it, as those who had undergone radiation had a lower risk among survivors.

Lead researcher Dr. Su-Min Jeong, from Seoul National University, explains, “This suggests that standard breast cancer treatments, including radiation therapy, may not increase and may even reduce Alzheimer’s dementia risk in the short term. Clinicians can use this evidence to reassure breast cancer patients concerned about their cognitive health.”

The team says further research is needed to see whether certain cancer treatments may be protective against Alzheimer’s.

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