The Chemobrain Phenomenon

© On the Brain—Posit Science

“One day, I put my sneakers in the freezer, blanked out on my sister’s birthday, and received a call from my son’s school because I’d forgotten to pick him up,” Suzanne, 35, recalls of her memory lapses during chemotherapy treatment for breast cancer.


Breast cancer survivor Laverne, 67, retired pharmaceutical representative, wasn’t sure if her memory problems were attributable to chemotherapy or to normal age-related cognitive decline. “I read that one of the side effects of the chemotherapy was memory loss, but the truth is I had senior moments before, during and after chemo. I can’t definitively say that I noticed a difference,” she laughs.


Suzanne and Laverne were responding to questions about their experiences with chemobrain or chemofog. According to the Mayo clinic, chemobrain “refers to cognitive changes during and after chemotherapy,” which can affect memory, the ability to find words, and the ability to manage multiple tasks and learn new things. The phenomenon affects about 20% to 30% of breast cancer patients who undergo chemotherapy.


Just as Suzanne and Laverne have different views on the subject of chemobrain, so do members of the medical profession. Some say that chemobrain is a real phenomenon associated with chemotherapy and point not only to the significant number of documented chemobrain cases, but also to the pivotal studies that exist on the subject. One study published in the Journal of Clinical Oncology (2000) showed that more patients who had undergone or were undergoing treatment “had moderate or severe cognitive impairment” compared with their “healthy” counterparts.Another study, printed in the Journal of the National Cancer Institute (1998), showed that women who on average had completed treatment two years prior still showed cognitive impairment, suggesting the long-term effect of chemo on the brain. 


However, others in the profession are not that certain about chemobrain, and argue that the added stress of chemotherapy to an otherwise busy schedule could have an impact on how a patient functions, as could reduced levels of estrogen, fatigue, anxiety and some of the medications used to mitigate the other side effects of chemotherapy. And a recent study in the Journal Cancer (2004) reported that perhaps chemobrain might not be attributed to chemotherapy at all, but to other factors not previously investigated. The study set out to evaluate the cognitive state of 84 women with cancer before undergoing chemotherapy. The results showed that, among other things, 35% of the women “exhibited cognitive impairment” and that “memory function (25%) [was] impaired more frequently relative to normative expectations” even prior to  chemotherapy treatment. The study concluded that studies regarding postchemotherapy cognitive impairment must include prechemotherapy cognitive evaluations.   


The debate will go on. But regardless of the genesis of chemobrain, Dr. Henry Mahncke, Vice President of Research and Outcomes for Posit Science, acknowledges the similarities between the symptoms associated with chemobrain and those associated with normal age-related cognitive decline, and points out that both phenomena have a direct impact on a person’s quality of life. He told On the Brain that Posit Science is currently developing a clinical trial to evaluate the use of the company’s Brain Fitness Program in breast cancer survivors undergoing chemotherapy. “As a corporation, we look forward to determining the impact of our cognitive fitness program and hope to provide benefit to the approximately 50,000 women with breast cancer undergoing chemotherapy each year.”