Breast cancer survivors who have endured mental fogginess and forgetfulness following chemotherapy can take some comfort in the fact that “chemo brain” has been validated as a condition. A study using functional neuroimaging has shown that chemotherapy affects the brain’s metabolism and blood flow, causing changes that can last at least 10 years following treatment. Because the majority of women diagnosed with breast cancer now achieve long-term survival, the lingering side-effects of treatment are an important consideration. Chemo-brain symptoms, which include confusion, disrupted thought processes, and difficulty focusing or multitasking, are experienced by at least 25 to 82 percent of survivors, according to estimates. Daniel H.S. Silverman and his colleagues at the University of California’s David Geffen Medical Center in Los Angeles used positron emission tomography (PET) and cognitive testing to investigate their subjects. They scanned the brains of 21 women who had undergone breast cancer surgery five to 10 years earlier, 16 of whom had been treated with chemotherapy near the time of their surgeries. These fluorodeoxyglucose PET images represent a horizontal slice through the brains of three women at rest, one of whom had breast cancer and received chemotherapy (far left). The other two images are from women who received no chemotherapy, one who had the disease (middle) and one who did not (right). The color reflects the metabolic activity of the brain cells — with the red, orange and yellow areas (in decreasing order) representing the most active regions and the green, blue and violet areas progressively showing the less active areas. The ages of the women were, from left to right, 55, 55 and 51. Courtesy of Daniel H.S. Silverman. They compared the images with brain scans of five breast cancer patients who had surgery only and with those of 13 control subjects who had neither the disease nor the treatment. As the women performed short-term memory exercises, the team measured blood flow to their brains. They also ran scans of the women’s resting brain metabolism after the women finished the exercises. The scans revealed a link between chemo-brain symptoms and lower metabolism in a key region of the frontal cortex. They showed that blood flow to the frontal cortex and cerebellum spiked as the chemotherapy patients performed the tests. This rapid jump in activity in these areas indicated that these women’s brains were working harder than the control subjects’ to recall information. The researchers also found that women who received hormonal therapy in addition to chemotherapy showed changes in the basal ganglia, a part of the brain that bridges thought to action. Additional studies are needed to determine how the alterations in the brain occur and the possible ways in which to prevent them, including modification of chemotherapy drugs. A long-term study of chemo-brain symptoms in a larger group of cancer survivors is planned. Breast Cancer Research and Treatment, online, Sept. 29, 2006.