Chemobrain: How much is actually caused by cancer treatments?

By Deborah Kotz, Globe Staff

Along with chemotherapy’s well-documented side effects of nausea and fatigue, cancer patients also complain about a type of brain fog that sets in clouding their memory, judgement, and cognitive abilities. But a new study presented Friday at a breast cancer conference in San Antonio suggests that the condition -- called “chemobrain” -- may not always be due to the drugs but to the stress and anxiety that comes from receiving the diagnosis and fears of impending treatment.

University of Michigan researchers came to this conclusion after performing brain scans on 28 breast cancer patients before and soon after chemotherapy and comparing them to brain scans in a similar number of patients undergoing radiation treatments as well as a healthy control group. They found that the breast cancer patients facing chemotherapy have higher levels of fatigue before the treatment and performed less accurately on verbal memory tests compared to the two other groups; they also had less activation on the MRI scans in certain areas of their brain needed to perform those memory tests.

Those women receiving radiation had more fatigue and cognitive difficulties before and after treatment -- that were also associated with less brain activity in certain regions -- compared to the healthy controls.

Any breast cancer patient who had diminished brain activity before treatment -- regardless of whether she had radiation or chemotherapy -- was more likely to report having the mental fogginess associated with chemobrain after completing treatment.

“What we’re suggesting is that we really need to be more aware that a woman facing breast cancer may have cognitive problems ahead of her treatment,” said study leader Bernadine Cimprich, an associate professor emerita at the University of Michigan School of Nursing in Ann Arbor. “Doctors or nurses should be asking if she’s having trouble concentrating, getting any work done, or taking care of her children.”

Previous research has shown that daily exercise can help breast cancer patients manage stress as well as meditation techniques like practicing mindfulness. “Placing oneself in a natural environment a few times a week can also help,” Cimprich added. Being surrounded by nature while gardening or taking an outdoor stroll enables the mind to focus on other things besides internal worries.

Implementing stress management techniques before treatment could help patients cope better after therapy begins and may reduce the likelihood of cognitive difficulties, she added.

That doesn’t mean, however, that chemobrain is, well, all in a patient’s head. It can, indeed, be caused by drugs or radiation used in cancer treatments. In a study presented last week at the Radiological Society of North America meeting, researchers used PET imaging scans to examine differences in brain metabolism in patients pre- and post-chemotherapy and found significant decreases in metabolism after chemotherapy in regions of the brain responsible for problem solving, organizing daily activities, and long term memory. These decreases correlated with symptoms reported by patients.

Just how much chemotherapy contributes to a drop in mental function that many cancer patients contend with isn’t known, Cimprich said. More than 25 studies have looked how often patients develop cognitive problems during chemotherapy and have found an incidence ranging from 17 percent to 78 percent, too big a range to get an accurate picture. Also unknown is how commonly it occurs in men, since it’s been mostly studied in female breast cancer patients.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.