Susie Brain always had a strong ability to juggle multiple tasks. But after she underwent intensive chemotherapy for breast cancer in 2004, she found she could no longer do so and eventually quit her job as executive director of a small, environmental nonprofit organization.

"When I finished treatment at the end of that year, I just didn't know what my head was doing. I tried to keep going with my work, but I found I could not," said Brain, now 61, of Palo Alto.

Brain is hardly the first to discover chemotherapy's after-effects.

The condition referred to by patients as "chemobrain" has been noted by many cancer patients before her, and now a recent Stanford University study validates their experiences and previous studies. Memory or cognitive problems following chemotherapy are real, the study concludes.

When brain functions were monitored by functional magnetic resonance imaging, or fMRI, women in the study group who had been treated with chemotherapy had significantly less activity in the part of the brain responsible for executive-functioning or problem-solving tasks than breast cancer patients who had not had chemotherapy.

Scans match impairment

The study, published in last week's Archives of Neurology journal, also found a strong correlation between the levels of cognitive impairment that patients reported they were experiencing and the decreased levels of activity detected on their brain scans.

"The higher they said their impairment was on a self rating, the lower their functional activation found" in the scans, said Shelli Kesler, assistant professor of psychiatry and behavioral sciences at Stanford and lead author of the study.

In other words, Kesler said, patients shouldn't be ignored when reporting symptoms, such as memory troubles or feeling "foggy." She said patients often dismiss their own symptoms, chalking them up to fatigue, stress or trauma.

The study, supported by the National Institutes of Health, involved 25 female breast cancer patients who had undergone chemotherapy and surgery and 19 breast cancer patients who had had surgery only. Eighteen healthy women were included to serve as the control group. While the study group may appear small, Kesler said the number is relatively large for a brain scan study.

Participants were screened for symptoms of stress, anxiety and fatigue to ensure that other conditions weren't affecting their cognitive function. They were then asked to perform card-sorting tasks and were found to have more trouble completing the exercises and make more mistakes than women who had not undergone chemotherapy.

Kesler said additional research is needed, in part to determine whether some patients who undergo chemotherapy are more vulnerable to cognitive problems than others. She said science also needs to establish how much of the difficulties are due to the chemotherapy and how much can be attributed to the disease itself.

"The theory is the tumor itself causes changes in your immune system," she said. "You get elevated inflammation, and those inflammatory factors do get into the brain, and they are toxic to brain cells."

Other cancer types affected

While her research focused on breast cancer patients, Kesler said the problem can affect patients who undergo chemotherapy for other forms of cancer.

Gay Crawford, a former breast cancer patient treated with surgery, had chemotherapy seven years ago for non-Hodgkin's lymphoma. She remembers doing things like going to the market and coming home only to realize that she left the entire grocery-laden cart in the store.

Even though her doctor had warned her about the possibility of cognitive impairment, she wasn't convinced. "At the time, I was attributing it maybe to the lack of sleep, but that could have been chemobrain," said Crawford, 67, of Saratoga.

Crawford said she believes she has since recovered.

That's the good news. Kesler said the brain is elastic, so patients can improve on their own or with cognitive rehabilitation. She said symptoms may last for months or years and vary by patient.

Brain believes the Stanford study has validated her experience. She now keeps herself busy as a volunteer board member and advocate with a number of different cancer organizations.

"I'm glad I can still juggle all these different activities I'm doing," she said. "I have all these fingers in the pie, and I'm still able to do that."