For years those that have received chemotherapy as part of their treatment for cancer have been reporting a set of neurological symptoms that include difficulties with short-term memory and decision-making that developed after receiving anti-cancer medical therapy. These symptoms, informally called “chemo-brain” or “chemo-fog,” are finally being recognized and studied by researchers in fields from psychology to cancer treatment. 1, 2
The symptoms attributed to chemo-brain are quite varied, but two subsets of these symptoms seem to be the most prevalent.
The first subset involves difficulties with what are known as the “executive functions” of the brain, the process by which the brain makes decisions regarding priorities or deciding on a course of action. As an example, those with chemo-brain have reported problems deciding in what sequence a set of actions, such as shopping at different locations, should be performed.
The second subset of symptoms, those involving problems with short-term memory, seems to be the most prevalent. Short-term memory is the process by which “new” information, such as a person’s name, is “remembered” until the brain makes a decision concerning whether the information should be retained or discarded. In another example, one woman reported that she was unable to remember the scores during her son’s high school tennis matches even though she had taught her son the game and was an accomplished amateur in her own right.
There are, of course, many medical conditions that are known to cause the same symptoms as those associated with chemo-brain. These conditions include:
· Stress, which is probably the most common cause of memory problems. Since treatment for cancer is both emotionally and physically stressful, researchers are investigating whether stress is a possible contributing factor in chemo-brain.
· Hormonal imbalances are also associated with difficulties involving both memory and executive functions. The fact that hormonal therapy is an important part of cancer therapy, particularly in women, has led some researchers to propose that chemo-brain may be related to changes in hormonal levels in chemotherapy.
The reader desiring more information on these topics will be well-served by consulting the links in the “For More Information” section of this posting.
As an aside, the symptoms reported in chemo-brain are very similar to those reported by patients that have undergone heart surgery using heart-lung bypass (meaning that the heart was stopped during surgery and the body’s oxygen requirements were met by using “the pump”). Interestingly, the growing use of “off-pump” surgical techniques (the heart is not stopped during surgery) has been associated with a dramatic decrease in post-operative neuro-psychological problems. 3, 4
Comment
The recent research activity involving the possible causes of “chemo-brain” is both encouraging and fascinating. Finally, this set of self-reported symptoms has caught the attention of the medical community. It is encouraging to the literally thousands of patients that have received “chemo” as part of their cancer treatment in that they now know that they are not alone; that their symptoms are now being recognized as a possible “side effect” of chemotherapy.
I find these reports fascinating in that the symptoms of “chemo-brain” are very similar to those that are associated with the earliest stages of conditions such as Alzheimer’s disease and “age-related cognitive decline.” Research data regarding the actual mechanisms by which chemotherapy induces these symptoms will be of great interest to those investigating how the brain encodes and stores memory in a variety of conditions.
For More Information
“Chemobrain: the hunt for answers” is an article that appears in the online version of the American Psychological Association’s journal Monitor on Psychology. The article is available at http://www.apa.org/monitor/apr05/chemobrain.html
The Mayo Clinic has published “Chemobrain: When cancer treatment disrupts your thinking and memory,” a well-written article with numerous links to related topics. It is available online at
http://www.mayoclinic.com/health/cancer-treatment/CA00044
Notes
1. Janette Vardy, Sean Rourke, and Ian F. Tannock (2007): Evaluation of Cognitive Function Associated With Chemotherapy: A Review of Published Studies and Recommendations for Future Research, J Clin Oncol Jun 10 2007: 2455-2463.
2. Ian F. Tannock, Tim A. Ahles, Patricia A. Ganz, and Frits S. van Dam (2004): Cognitive Impairment Associated with Chemotherapy for Cancer: Report of a Workshop, J Clin Oncol Jun 1 2004: 2233-2239.
3. OA Selnes, MA Grega, LM Borowicz Jr, S Barry, S Zeger, and McKhann GM (2004): Self-reported memory symptoms with coronary artery disease: a prospective study of CABG patients and nonsurgical controls, Cogn Behav Neurol. 17(3):148-56.
4. PV Raja, JA Blumenthal, and PM Doraiswamy (2004): Cognitive deficits following coronary artery bypass grafting: prevalence, prognosis, and therapeutic strategies, CNS Spectr. 9(10):763-72.
