Cancer patients have long known about the foggy-headed feeling they felt after treatment, calling it “chemo brain,” but scientists only started studying it fairly recently. Now there’s growing evidence, including studies done at City of Hope, that this mental haze is real and is based on changes in the brain.

Sunita Patel is studying the factors behind “chemo brain.” (Photo by Alicia Di Rado)

Called cancer-related cognitive dysfunction by scientists, it’s a change in your ability to think and remember linked to the diagnosis of cancer and its treatment, explains Sunita K. Patel, Ph.D., clinical neuropsychologist and assistant professor at City of Hope. She studies the phenomenon, which commonly includes difficulty concentrating, paying attention or reacting quickly.

The American Cancer Society recently awarded Patel a grant to continue her investigations into chemo brain among women with breast cancer. She’s studying women before and after cancer treatment to see whether cancer drugs cause the symptoms or if the problem comes from cancer itself. She also wants to know if certain women are at greater risk.

One recent study suggested that treatment is to blame for struggles in thinking. Researchers in New York showed that certain areas of the brain were less active in women who’d undergone chemotherapy for breast cancer than in women who hadn’t undergone chemotherapy. These included sections critical to working memory, attention and executive function — mental processes people use to plan, organize and come up with strategies.

Women in the study either had breast cancer and had undergone chemotherapy, had breast cancer and didn’t undergo chemotherapy or were cancer-free.

The researchers performed functional magnetic resonance imaging, or fMRI, scans on the women while the women sorted cards. The sorting task tested the women’s problem-solving abilities.

They found that women with breast cancer — regardless of whether they’d had treatment — had less activity in the prefrontal cortex, an area of the brain important to problem-solving and complex thought. But only the women who’d undergone chemotherapy had trouble with the card-sorting test.

No one knows why chemotherapy might affect the brain. It may affect neural stem cells. Or it might increase inflammation or damage the inner workings of certain cells. But for now, Patel underscores the good news: Symptoms generally disappear over time.

She suggests a variety of practical coping strategies to deal with memory and cognitive struggles during and after treatment.

If patients continue to have difficulties after several months to a year following the end of their cancer treatments, Patel recommends they consult their doctor about getting a comprehensive neuropsychological evaluation.