Many people living with cancer are familiar with so-called brain fog or chemo brain during treatment—but could cancer actually protect against memory problems over the longer term?

Monica Ospina-Romero, MD, of the University of California at San Francisco, and colleagues compared long-term memory changes in more than 14,500 Americans older than 70 in the Health and Retirement Study. During an average follow-up period of 12 years, about 15% were diagnosed with cancer. 

People with cancer had modestly higher average memory scores than those of a similar age who did not develop cancer. The rate of memory decline in the decade before a cancer diagnosis was about 11% slower than the decline seen in cancer-free people of a similar age. And even after diagnosis, the decline was about 4% slower.

These findings show that cancer may have a protective effect against cognitive impairment—and prior studies have indeed found that people with a history of cancer have a lower likelihood of developing Alzheimer’s disease. “These novel findings support the possibility of a common pathologic process working in opposite directions” in cancer and Alzheimer’s, the researchers suggested.