The memory lapses and concentration problems that some cancer patients experience after chemotherapy -- what many call "chemo brain" -- may be caused by physical changes in the brain after treatment, a new study suggests. The finding, though preliminary, opens the door for strategies that might help prevent this side effect, said lead researcher Daniel Silverman, MD, PhD, of the University of California, Los Angeles.

Silverman and his colleagues looked at brain activity in 21 breast cancer survivors (some of whom had been treated with chemotherapy and some who had not) and a handful of women who had never had breast cancer. The women were asked to perform some simple memory tasks while getting PET scans to measure blood flow in parts of their brains. Then another scan was taken to measure the metabolism of their brain at rest.

The researchers found important differences between the groups. The women who had received chemotherapy had greater blood flow to certain areas of their brain during the memory tasks (indicating these areas were working harder), compared to the women who had not had chemotherapy. And the chemotherapy group had a lower resting metabolism in these areas of the brain than the other groups.

"The same area of the brain that was most different when performing the tasks was the area that had the most decrease in metabolism in the women who had the most severe symptoms [of chemo brain]," Silverman explained. "What that in effect says is happening is that… their brains have to work harder to perform the same tasks."

Of course, this study was very small and couldn't prove definitively that chemotherapy harms certain brain functions. But Silverman said it is a necessary first step to additional research on the subject.

He and his colleagues are now beginning a larger study that will measure breast cancer patients' brain function before treatment as well as after to see what effect chemotherapy has. That study and others like it may also help doctors figure out whether specific drugs are causing the problem and how. Those findings could help not only breast cancer patients, but any patient who gets chemotherapy. Breast cancer patients are usually the ones studied in chemo brain research because so many of them get chemotherapy and live long healthy lives afterward.

Silverman said the results of this research also could eventually lead to ways to prevent chemo brain, if these initial findings hold true. Brain scans before treatment may help doctors identify patients most at risk of developing chemo brain -- and that could help them make decisions about the risks and benefits of chemotherapy.

Silverman also foresees a day when patients could be monitored for brain damage during chemotherapy just as they are currently monitored for heart damage when they get drugs known to harm the heart. Brain scans would allow doctors to see the effects on the brain -- and stop or change treatment -- before they caused the patient any problems.

Citation: "Altered frontocortical, cerebellar, and basal ganglia activity in adjuvant-treated breast cancer survivors 5-10 years after chemotherapy." Published online Oct. 5, 2006, in Breast Cancer Research and Treatment. First author: Daniel H.S. Silverman, MD, PhD, University of California, Los Angeles.