The Chemobrain Mystery
Researchers are confirming what many women already know—cancer treatment can cause memory loss. But is chemotherapy always to blame?
By Patricia Prijatel
Cissy Taylor, 60, of Manchester, New Hampshire, was an avid reader and a crime reporter who routinely covered homicides and undercover drug buys before she was diagnosed with stage II breast cancer in 2003. A month into chemotherapy, she could no longer focus on what she was reading.
“I couldn’t retain information,” she says. “I’d forget what I had read the day before.”
The loss was especially significant to Taylor. She had to give up her newspaper job of 37 years and take on less-demanding freelance assignments. Simple household tasks—programming the VCR, doing small home repairs—also became too much for her. “I can’t follow written instructions,” she says. “I can’t put the whole picture together.”
Researchers now believe that 20 to 30 percent of breast cancer patients face similar memory and attention problems. Women have dubbed the phenomenon “chemobrain” or “chemo fog,” but in fact, the real cause may not be chemotherapy alone. The culprit might be a variety of treatment effects, genetic factors or even the disease itself. It’s also not known whether any cases are attributable to natural aging, though younger women do report cognitive issues as well, or to another cause.
Whatever the reason, it’s clear that these mental lapses are real and have a significant impact on women’s lives. In a recent survey by the Hurricane Voices Breast Cancer Foundation, more than 50 percent of respondents reported “moderate” to “severe” changes in cognitive categories such as word recall, short-term memory, concentration and multitasking ability. The cumulative effect, though, was even more significant, with survivors saying their self-confidence and faith in their own capabilities had decreased so much that their jobs and home lives suffered. “What I found most striking is that people talked about losing a sense of self,” says Janet Colantuono, Hurricane Voices’ executive director. “They were no longer the person they were before treatment.” Because doctors sometimes dismiss patients’ complaints about memory loss, Colantuono hopes the survey will help women to feel more supported to begin a conversation with their physicians. “As more and more of this research comes to the fore, the medical community has opened its eyes and ears,” she says.
Scanning for answersMapping changes in the brain is complex work, made more so by the varied and interconnected treatments for breast cancer—surgery, anesthesia, chemotherapy and hormonal therapy—that can all have a role in cognitive change. That is not to mention the disease itself and the stress it brings. What’s more, cognitive changes may be so subtle that testing mechanisms are not yet able to detect them. And doctors have no measure of what might be normal for each individual. Some patients with average scores on cognitive tests might have scored far higher before they became ill.
“They tell me my scores are good. But I know they’re not good for me,” says Sylvia Roberts, M.D., 54, who had to give up her internal medicine practice after unusually aggressive treatment for locally advanced stage III breast cancer left her mentally and physically fatigued. Before her diagnosis 13 years ago, she had been the “queen of multitasking” who had two children during the years she was in medical school and residency. Now an assistant clinical professor of medicine, Roberts says the coping mechanisms she’d learned in medical school, like tricks to remember names, helped her “cheat” on neuropsychological tests that measured her memory and attention skills. Still, she says, “I am not exactly what I used to be, and I don’t think I ever will be.”
A study published in the September 2007 issue of the Journal of Clinical Oncology on a pair of 60-year-old twins—one of whom had breast cancer—provides an intriguing look at the complexity of cancer-related brain damage. Both twins had similar scores on standardized neuropsychological tests; yet, when the two women took the same tests while undergoing magnetic resonance imaging (MRI), it was clear that the brain of the woman who had had cancer treatment—surgery, chemotherapy and tamoxifen—had to work far harder to keep up.
“She had to recruit different areas of her brain,” says Tim A. Ahles, Ph.D., one of the project’s researchers and a behavioral psychologist at Memorial Sloan-Kettering Cancer Center in New York City. This compensation, he says, may be why some women report that their symptoms are worse under stress, which can interfere with the brain’s efficiency. This also makes it harder for doctors to isolate cognitive changes using only standardized tests. Ahles says imaging techniques and brain scans play an important role in helping researchers understand changes in the brain associated with cancer treatment.
Brain images demonstrate that these changes have a measurable physical basis, says Daniel Silverman, M.D., Ph.D., head of the Neuronuclear Imaging Section of the Ahmanson Biological Imaging Division at the University of California–Los Angeles Medical Center. In a clinical trial published in the October 2006 issue of the journal Breast Cancer Research and Treatment, Silverman and his colleagues used three-dimensional PET scans to study the correlation between brain activity and the results of standardized cognitive tests on women with breast cancer. Those who scored lowest on short-term memory tests showed alterations in their frontal cortex, the part of the brain that manages the ability to retain and recall recent events or experiences.
“It’s as if they had to work that part of the brain harder to function normally,” Silverman says.
Women who had chemotherapy plus tamoxifen showed reduction in their basal ganglia, the deep brain structures that act as “a bridge between thought and action,” Silverman says. This affects a woman’s ability to organize and carry out a plan. Chemo dosage is another factor; patients given high doses are likely to suffer more damage than those treated with standard chemotherapy.
As part of an experimental treatment, Roberts had a far heavier dose of chemicals than most women now face. She was aware that she could experience long-term effects, but she was determined to see her two small children grow up. Today, despite the lingering problems, Roberts is grateful to be alive, and she looks forward to seeing her children, now in college, make her a grandmother one day.