ATLANTA (AP) _ Anti-cancer drugs may not be entirely to blame for the mild mental impairment suffered by some cancer patients undergoing chemotherapy, a study found.
The findings suggest the forgetfulness and other symptoms associated with so-called ``chemobrain'' may be caused by cancer itself rather than potent cancer-fighting medicines, researchers said in a study published Monday in the online version of the journal Cancer.
In a study of 84 breast cancer patients diagnosed with neurological problems, 35 percent reported cognitive problems before receiving chemotherapy drugs. Chemotherapy did cause a mental decline in the other patients.
The study was the first of its kind to find cognitive impairment in cancer patients prior to receiving chemotherapy. Other symptoms of the disorder include difficulty speaking or interacting socially.
In the past, doctors may have assumed all cognitive impairment found after chemotherapy stemmed from anti-cancer drugs because physicians never examined a patient for mental decline prior to treatment, said Dr. Christina Myers, professor of neuropsychology at the M.D. Anderson Cancer Center in Houston and one of the study's authors.
``They only looked at one point in time, and any problems they attributed to chemotherapy,'' Myers said. ``The situation is more complex.''
About half the patients in the study reported recovering from the mental symptoms within a year of receiving chemotherapy.
The findings are important because some cancer patients have been hesitant to undergo chemotherapy out of fear of developing post-treatment problems, including chemobrain.
``I think for most people, they're willing to expose themselves to adverse effects of a therapy that will prolong their life,'' Myers said.
The study also provides scientific data on chemobrain, not just anecdotal evidence, said Dr. Mary Simmonds, a medical oncologist and former national president of the American Cancer Society.
``It's human nature. If I were the patient, maybe I would be like any normal person and blame the drugs, but that's not always the case,'' Simmonds said.
Cancer doctors are not sure why patients with cancer develop neurological problems. Cancer cells could create substances that impair the nervous system, or the immune system could create an inflammatory response to cancer that could be responsible for the fuzzy mental symptoms, Myers said.