A new study has reported that both chemotherapy and radiotherapy are associated with reduced cognitive functioning ("chemo brain") in breast cancer patients and that these impairments persist for at least three and one-half years after treatment. The study included 129 women with stage 0-II breast cancer, of whom 62 were treated with both chemotherapy and radiotherapy and 67 received radiation only. In addition, 184 women with no history of cancer served as controls. The breast cancer patients completed neuropsychological assessments six months after finishing treatment and again three years later. The controls were tested over a similar interval.
The cancer-free controls performed significantly better on executive functioning measures than the chemotherapy plus radiotherapy and radiotherapy only groups over time. Executive functioning refers to the ability to organize thoughts and activities, manage time well, prioritize tasks, and make decisions. The processing speed of the cancer-free controls, but not the radiotherapy only or chemotherapy plus radiotherapy groups, also tended to improve over time. Processing speed refers to the ability to automatically and fluently perform relatively easy or routine cognitive tasks, especially when high mental efficiency (i.e., attention and focused concentration) is required. Further analyses found that anti-estrogen treatments (aromatase inhibitors or tamoxifen) were not found to be associated with changes in cognitive performance over time. The authors conclude that the study findings provide limited support for the view that changes in cognitive functioning in cancer survivors are attributable to chemotherapy and radiotherapy. Future research should seek to establish mechanisms that could explain the apparent prolonged impact of both chemotherapy and radiotherapy on cognitive functioning in breast cancer survivors.
What happens after chemo brain?
This is not the first study to have found that radiation treatment can result in chemo brain even in the absence of chemotherapy. However, the mechanism of action of radiation treatment on cognitive functioning has not been explained. Breast cancer survivors who develop chemo brain want to know how long it will last and the long-term implications of what is now is understood to be physiological brain damage (and not an artifact of depression or other emotional response to breast cancer diagnosis and treatment as was once thought). Chemo brain does not appear constitute a direct path to dementia in old age. In fact, cancer survivors are less likely to develop Alzheimer's disease than the general population, for reasons that are not understood. However, as the present study shows, chemo brain can be persistent.
Since so little published data is available concerning the course of chemo brain, I am going to make some personal comments which I hope some of you will find helpful. I had what was probably a rather severe case of chemo brain (along with terrible headaches) as a result of chemotherapy. I found that I could not trust my brain to execute what had once been fairly automatic tasks. I misspelled the middle name of one of my sons on an important form for a summer internship. I found myself staring at common words such as "through" and not being sure what they meant. I lost my way on Los Angeles freeways that I had travelled thousands of times. My lapses were emotionally threatening to my husband and sons and they responded with a certain amount of vigilance and teasing (not funny, as far as I was concerned). I tried to cover up my cognitive impairments and to concentrate harder in areas I knew could be a problem. However, I kept slipping up, such as the time I pointed to a car similar to ours (not the car we had arrived in) 60 miles from home and commented that I thought we had already fixed the broken headlight.
Six years later, I have recovered approximately 90% of the cognitive functioning that I lost as a result of chemotherapy. The improvement has levelled off. I wish that the above study had been extended further to capture this type of recovery. In my case, the two-year mark was the turning point, after which my symptoms started to abate. I am young enough that I never thought that I was slipping into a permanent mental fog. However, I think that, like other brain injuries, chemo brain is likely to have long-term consequences for some people. I find that over-the-counter sleep aids such as Tylenol PM and narcotic pain killers can revive my chemo brain symptoms to some extent and I avoid them. Exercise appears to sharpen my thinking. — Sarah Charles