More than a third of women with breast cancer may have some degree of cognitive impairment before undergoing chemotherapy, according to a new report. This suggests that the disease itself rather than the treatment may be responsible for so-called “chemobrain.”

Chemotherapy has been linked to changes in mental functioning in women with breast cancer, the researchers explain in the medical journal Cancer, but neuropsychological functioning has rarely been measured before treatment.

Dr. Christina A. Meyers from The University of Texas M. D. Anderson Cancer Center, Houston, and colleagues evaluated data from three separate studies that examined the effects of different treatments on the mental abilities of women with breast cancer. All the women underwent a comprehensive neuropsychological evaluation before treatment.

Approximately 35 percent of women were classified as having an impaired Cognitive Function Index before beginning chemotherapy, the authors report. Changes were most apparent in verbal learning and verbal memory, as well as attention.

About a quarter of the women reported symptoms of anxiety and/or depression that indicated clinically significant distress, the team found. These women were also more likely to show cognitive impairment.

“Chemobrain is real,” Meyers told Reuters Health. “It can be caused by the cancer, the cancer treatment, or other underlying medical conditions (borderline anemia, thyroid dysfunction, etc.), and it can be treated.”

Her advice to patients is ‘tell your doctor.’

“There are a number of things that can cause symptoms, so identification of what is wrong and why is important to guide interventions,” Meyers said. “And we do have a number of interventions to attenuate the impact of adverse symptoms on the patients’ ability to function.”

Her team is looking at “how these symptoms develop and who gets them, so we can develop targeted and effective treatment.”

SOURCE: Cancer, June 21, 2004.