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Study What causes the cognitive impairment of breast cancer patients?
Many breast cancer patients show mild impairment of their cognitive abilities, which is often associated with the side effects of chemotherapy. A research team led by Dr. med. However, Kerstin Hermelink from the Breast Center of the Ludwig-Maximilians University (LMU) has shown in a recent study that the impairment also occurs in breast cancer patients without chemotherapy. The cause is post-traumatic stress.
"Mild cognitive disorders in breast cancer patients can occur equally with and without chemotherapy and are associated with post-traumatic stress," the researchers report on their study results. The suspicion of a connection with the side effects of chemotherapy was not confirmed. The so-called "Chemobrain" is therefore a myth. Rather, the impairments are a consequence of post-traumatic stress.
Breast cancer patients often show impairments of cognitive functions, which according to recent studies are due to mental stress. (Image: WavebreakMediaMicro / fotolia.com) Changes in cognitive performance are examined
In their study, scientists studied 166 women who had previously been re-diagnosed with breast cancer, which changes in cognitive performance. As a control group served 60 women, in which a routine breast examination had no suspicion of cancer. All subjects were examined for posttraumatic symptoms by means of a clinical interview at three appointments within one year, and their cognitive functions were extensively tested with neuropsychological procedures, the researchers report.
Impairments in all breast cancer patients
The scientists observed that one year after breast cancer diagnosis, the patients had minimal cognitive abnormalities. However, this applies both to patients after chemotherapy and to patients who had been treated without chemotherapy. Compared with the participants in the control group, the breast cancer patients had shown a slight, just verifiable decrease in their test performance. The abnormalities "were related to the severity of posttraumatic symptoms and the effect of cancer on attention was no longer statistically significant when the effect of post-traumatic stress was considered," the researchers report.
Reaction time minimally affected by chemotherapy
According to the researchers, chemotherapy will have no further impact on cognitive abilities. "Only one salient neuropsychological result occurred exclusively in chemotherapy patients and had nothing to do with post-traumatic symptoms," the scientists report. For example, a few months after completing chemotherapy, the patients showed slightly longer reaction times in a computer-based test, which required them to click as soon as a cross appeared on the screen. However, the minimal difference of 19 milliseconds on average could have been caused by peripheral neuropathy, damage to the finger nerves by certain cytostatics, and nothing to do with cognitive functions, study director Hermelink said.
Psychological factors of the triggers
Overall, the study results suggest that cognitive function disorders in cancer patients are more likely to be due to psychological factors than to neurotoxic side effects of treatment, the researchers write. "Our brain is not a machine that always works the same way, but it constantly changes its functioning and its structure depending on what we do and experience," emphasizes the study leader. Here, the effects of psychological stress on cancer patients seem almost logical. "It would be strange if all that cancer brings to the psyche and to life interventions would leave its mark on the brain and cognitive functions without trace," Hermelink said. In addition, it was "well established that post-traumatic stress - not to be confused with normal everyday stress - deeply interferes with the functioning of the brain."
Chemotherapy without detriment to the cognitive functions
While scientists in the current study focused on the effects of posttraumatic stress, insomnia, anxiety, depression and other factors may play a role in cognitive impairment, according to the experts. In research on cognitive disorders in cancer patients, such factors have been neglected so far. For breast cancer patients, however, the current study results also contain good news, because they do not have to expect to suffer from neurotoxic effects of chemotherapy inevitably damage their cognitive functions, stress the scientists. (Fp)