Carolyn Vachani, RN, MSN, AOCN
The Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 5 de mayo del 2008
Many survivors who have previously received or are currently undergoing chemotherapy report experiencing cognitive changes, often referred to as "chemo-brain." These changes include difficulty with short-term memory, multi-tasking, new learning, reading comprehension, and working with numbers, as well as a decrease in concentration ability. For many years, this was attributed by physicians and researchers to depression or anxiety over the diagnosis and treatment of cancer. More recently, researchers have begun to study and document what survivors have been saying all along; cognitive changes after chemotherapy are real. Although we are not yet able to pinpoint whether only certain chemotherapy drugs are responsible for these cognitive changes, it seems certain that the effects are cumulative. That is, those who receive more chemotherapy tend to experience greater deficits. Studies have found that cognitive ability can improve over time in some survivors, but deficits are still present in many survivors, even years after treatment.
Two studies recently presented at the annual meeting of the American Academy of Neurology prompted health news reports to claim that "chemo-brain" may be a myth. These reports fly in the face of millions of survivors' accounts and numerous research studies (one that was presented at the same meeting). As is often the case, these news snippets don't report the whole story, so let's take a look at these studies and some of the research on this topic.
The two abstract presentations addressed in the recent news were both small in size (30 women and 17 women, respectively) and evaluated breast cancer patients in areas of memory, anxiety, depression, and quality of life. Both studies found that cognitive function was impaired when compared with control patients even prior to beginning therapy for their cancer, suggesting that anxiety over diagnosis and treatment decisions may play a role. One study found that one's mental "speed of detection" declined significantly after therapy, and 10% (3) of the women had developed cognitive impairment. The second study found poorer performance on memory and "speed of information processing" testing when comparing women with a new diagnosis to those who were at least 1 year post treatment. While these studies found differences pre-treatment, one did not evaluate function after therapy while the second stated in the conclusion that a rate of 10% for cognitive impairment 1 month after treatment was "infrequent".
Unfortunately, much of the research that has been done regarding "chemo-brain" evaluated small numbers of patients. Studying this issue is particularly difficult given the extensive variety of treatments and combinations of therapies used to treat different cancer diagnoses. On top of these differences, patients have varying levels of anxiety, depression and support when it comes to dealing with the diagnosis, treatment decisions and post-therapy issues. So, while patients have reported this phenomenon since the 1970's, it is only recently that physicians and researchers have begun to acknowledge the effect of therapy on cognition. This attention has led to the formation of a multidisciplinary "International Cognition and Cancer Task Force", which aims to address issues facing cognitive research in cancer survivors.
While this side effect has been unofficially named "chemo-brain", researchers have found that chemotherapy is not the only culprit. Radiation therapy (particularly involving the brain), biologic therapies and hormone therapies have also been implicated. Other health problems and the cancer itself may also contribute, and as the above studies noted, the anxiety of diagnosis likely plays a role as well. Many experts have proposed renaming this phenomenon, given the various possible causes, but that change has not yet occurred.
Studies have reported "chemo-brain" in anywhere from 15-50% or more of survivors who had received chemotherapy. Deficits may include impairments in attention, concentration, memory (visual and verbal), and processing speed. These may resolve over time, but in some survivors can persist for years after therapy. This may affect a survivor's ability to perform his/her job or manage family responsibilities. Some studies have seen declines in cognitive function, while others have not, and it is uncertain if these inconsistencies are due to various therapies or the numerous study designs and methods used to test for changes in function. Studies using radiologic imaging have shown differences in the brain functioning of survivors when compared to control groups, even in patients who perform well on cognitive function tests, providing some "evidence" that differences do exist. No mechanism for how cognitive decline develops has been clearly identified, and research is also needed in this area.
What does all of this mean for the survivor struggling to manage daily tasks? Researchers have begun evaluating "treatments" for the condition, and while there are no interventions that have been proven in studies, there are a few that can help a survivor cope while research continues.
Some medications are being studied as potential treatments for cognitive changes, but there is not yet enough data to support their use. Some of the agents being studied include: methylphenidate (Ritalin), modafinil (a medication approved to treat narcolepsy), various antidepressants, herbal therapies, such as ginkgo biloba or ginseng, and certain amino acids. Cognitive rehabilitation programs are structured programs utilizing exercise, tasks that use memory, and puzzles to "rehabilitate" one's mind. These programs are typically used for people with brain injuries, but therapists have tailored programs for cancer survivors. Bookstores and websites offer memory training, which may be helpful to survivors. Puzzles using numbers, like Sodoku, may help "exercise" your brain. Fatigue can enhance cognitive problems, so avoiding fatigue by getting enough sleep, incorporating exercise into your life, and eating a healthy diet may be helpful.
It is important to remember that some very treatable problems can result in cognitive difficulties, such as thyroid dysfunction, depression, and anxiety, so it is important to exclude or treat these diagnoses. Hypothyroidism (low thyroid hormone levels) is a common issue for survivors and can make you feel "fuzzy" or "out of it." This is easily treatable with supplemental thyroid hormone. Survivors who may be depressed or experiencing anxiety would benefit from consulting with a psychiatrist or psychologist experienced in working with cancer patients or survivors.
Research will continue into this issue, but in the meantime, survivors will need to incorporate their own solutions to make life a bit easier.
Boivin, MJ et al. Cognitive Impairment in Women Newly Diagnosed with Breast Cancer (abstract), American Academy of Neurology annual meeting, 2008.
Darby, DG et al. The Acute Cognitive Effects of Adjuvant Chemotherapy in Women with Breast Cancer (abstract), American Academy of Neurology annual meeting, 2008.
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Schagen, S. B. and J. Vardy (2007). "Cognitive dysfunction in people with cancer." Lancet Oncol8(10): 852-3.
Vardy, J., S. Rourke, et al. (2007). "Evaluation of cognitive function associated with chemotherapy: a review of published studies and recommendations for future research." J Clin Oncol25(17): 2455-63.
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