This often-unexpected side effect of cancer treatment leaves many patients experiencing debilitating cognitive effects after chemotherapy. Luckily, research and awareness are catching up.
By Beverly Burmeier
Ten years ago Sharon Palmatory’s trouble remembering names and numbers after chemotherapy treatment for breast cancer might have been brushed aside as an insignificant occurrence, considering survival was the primary concern. But today, thanks to early diagnosis and effective treatment, more women survive breast cancer than ever before, and quality-of-life issues like this are increasingly important.
“It’s a definite medical condition,” says Dr. Christina Meyers, PhD, ABPP, professor of neuropsychology in the Department of Neuro-Oncology at M. D. Anderson Cancer Center in Houston, describing what has come to be known as “chemo brain,” a lesser-known side effect of chemotherapy, which can be just as serious as nausea, fatigue, and hair loss. Thankfully, the condition—marked by a reduction in verbal or visual memory, problems with attention and concentration, a reduction in the speed of processing information, and visual or spatial abnormalities—is the subject of several recent studies, as researchers seek clues to the cause and the cure of this foggy mental condition.1
“Those involved in long-term follow-up care for survivors are well aware of their patients’ complaints that they cannot mentally function as well after treatment as before,” says Dr. Mark Noble, professor of genetics at the University of Rochester School of Medicine and Dentistry in Rochester, New York. Too many people are affected to ignore the syndrome—and not just breast cancer patients or women. Men experience the foggy mental state associated with chemotherapy, too. As a result, oncologists and nurses now make a better effort to provide patients with information about the possibility of cognitive impairment occurring either during or after active treatment.
Still, many patients are surprised by the debilitating impact of the condition. “I honestly didn’t know this would happen,” says Sharon, 39, of Morgantown, West Virginia. “I was more concerned with fatigue and taking care of my family.” But after her second chemotherapy treatment, she went into a general fog for a week. “I couldn’t multitask,” she says of the way the devastating side effect affected her demanding career as a multimedia designer for government projects. “Losing my train of thought was scary. And I couldn’t manage the household, remember names and numbers, or balance my checkbook.”
Following her fourth treatment, Sharon hit her lowest point, after which improvement started slowly. “I still have a one-track mind, although treatment ended several months ago,” she says. “I always have a pad of paper to write things down.” She laughs that at her age she can’t attribute these lapses to senior moments. “I rely on my husband to remind me of appointments. The exit door to my garage is plastered with notes.”
Doctors used to think that impaired cognitive ability was related to other side effects of chemotherapy. Anemia, fatigue, depression, and hormonal shifts can all cause memory lapses and concentration difficulties. But treating these conditions didn’t solve the problem for many patients. And assessing the severity was difficult because there was no baseline data of mental function before chemotherapy.2
“We now know that chemo brain is a manifestation of central nervous system toxicity that occurs in many cancer patients on active therapy and may persist for 45 percent of patients after treatment is discontinued,” says Dr. Meyers. Researchers also believe that some people have genes that make cancer more responsive to treatment. This puts normal tissue at risk for changes and makes them more susceptible to mental effects from chemotherapy.
“We know a fair deal about the damage done to the brain by radiation but virtually nothing about the effects of chemotherapy,” says Dr. Noble. “Imaging studies have shown clearly that high doses of chemotherapy result in changes.” What isn’t known yet is which chemotherapy drugs cause problems and how.
Fortunately for breast cancer patients (the type of cancer most frequently studied for cognitive impairment), chemo brain is currently a hot topic in the lab. Researchers are discovering more about how the brain and the nervous system are affected by toxic drugs used in chemotherapy. Still, not everyone is affected, and scientists haven’t ferreted out enough clues to determine who is at risk.
With aggressive treatment the cure rate for Stage I cancers has grown as high as 90 percent, yet not every woman with breast cancer needs chemotherapy, although most get it, says S. David Nathanson, MD, surgical oncologist at Henry Ford Health System in Detroit. That’s significant because up to 25 percent of women who do receive it will be affected by chemo brain—a statistic that complicates the decision about who should get chemo.
Despite advances in brain research during the past decade, the exact mechanisms for cognitive impairment aren’t clearly understood, although it’s recognized that standard chemotherapeutic agents can kill normal brain cells. Dr. Noble’s research is attempting to understand how stem cells function, with the hope of using them to prevent abnormal reactions or to successfully repair damaged tissue.
“If we can’t prevent the damage, can we repair it by stem cell or precursor cell transplantation?” he asks. “It may be possible to use brain cell transplantation to restore normal function, much as bone marrow transplantation is used to restore normal function of the hematopoietic system (organs and tissues involved in the production of blood) following cancer treatment,” he says.
Dr. Noble explains further: “In many ways, a cancer cell can be thought of as the evil sibling of a stem cell. Understanding the features that distinguish cancer cells from normal cells may enable cancer-specific treatments to be developed without negatively affecting quality of life for long-term survivors.” It may also help researchers develop a means of selectively protecting normal cells from damage caused by radiation and chemotherapy.
“The only way to prevent or treat cognitive impairment associated with cancer therapy is to understand why it occurs,” Dr. Noble adds. “One of our concerns is to be able to better understand the reason for different outcomes. Understanding why some people are resistant to these effects will enable us to protect those who are more vulnerable, perhaps by modifying treatment accordingly.”
Two major studies are being conducted at the University of Sydney Cancer Centre in Australia by oncologist Janette Vardy, MD. By studying brain scans and blood tests from breast cancer patients (other research is with colorectal cancer), her team has found that those who never received chemotherapy, although they had breast cancer, had functional MRI scans more like those of healthy control persons—and different from those of patients who had received chemotherapy. “What we don’t know is how those scanned differences will relate to how a person copes in normal life,” Dr. Vardy says.
In tests on the central nervous systems of experimental animals, Dr. Noble’s team has found that during chemotherapy there is a long-lasting reduction in cell division in the hippocampus of the brain, an action believed necessary for normal memory function. “Our work shows that there is damage to the insulation (myelin) that surrounds axons, with eventual loss of the cells that produce the myelin. A lack of myelin could also cause cognitive problems.”
Breakthroughs may also result from research by Jame Abraham, MD, director of the Comprehensive Breast Cancer Program at West Virginia University’s Mary Babb Randolph Cancer Center. His team is one of the first to investigate which specific changes in the brain lead to memory loss. Early research shows differences in the white matter in the front part of the brain in women who had received chemotherapy—differences that correlate with their slower speed in processing information. “Our preliminary findings suggest that chemotherapy may change the brain, and those changes affect the patient’s cognitive skill,” Dr. Abraham says. West Virginia University researchers also concluded that these changes do not appear to be caused by depression or anxiety.3 For those affected, Dr. Abraham’s research regarding direct damage to the brain from chemotherapy brings validation to their claims.
Sharon Palmatory, a patient of Dr. Abraham’s, has suffered typical side effects from her treatment. She explains: “I feel like I’m always two paces behind—always struggling to keep up. When I lose my train of thought, it’s hard to get it back.” The problem was severe enough for her to request a transfer to slower-paced work with less aggressive deadlines. (Dr. Meyers says 14 percent of affected people have to discontinue work altogether.) “I couldn’t predict my reaction to treatment on any given day,” says Sharon. Disorganization and distractibility, when it occurred, affected her ability to perform at her previous level.
Although ongoing research is bringing physicians closer to developing targeted treatments for preventing or treating chemo brain, patients like Sharon are left to cope with various levels of cognitive impairment. Many will recover normal or near-normal levels a year or two after chemotherapy, but quality of life in the interim requires implementing strategies for dealing with the mental haze. “Maintaining function is important,” says Dr. Meyers. Sharon agrees, saying brain function is a “use it or lose it” issue.
In an instructional video provided to patients, Dr. Meyers outlines several types of cognitive impairment that fall under the “chemo brain” label:
“Although it can be aggravating, having chemo brain is better than the alternative,” reminds Dr. Meyers. After ruling out other possible causes of memory problems, such as stress, depression, or medications, you can help yourself cope by incorporating these suggestions into your daily routine 4:
Regarding software products that are marketed as memory-building tools, Dr. Meyers says that repetitive mental exercises just don’t work. “You might get better at the specific game, but the skills don’t carry over to your life. For example, you might get better at Nintendo and still forget your friend’s name.”
At this point no drugs have proved successful for combating the effects of brain tissue damage. A small study conducted by Sadhna Kohli, research assistant professor at University of Rochester, showed improvement in memory, concentration, and learning for people taking Provigil® (modafinil), a drug that stimulates the brain only as required and lasts about 12 hours. Unlike Ritalin® (methylphenidate), which some patients have tried, Provigil is nonaddictive.
It’s also important that doctors assess and treat possible contributing factors such as thyroid dysfunction, hormonal imbalance, or anemia. As researchers come to better understand the mechanisms of chemo brain, genetic factors may play a larger part in treatment plans.
Sharon has found help close to home. Her mother is also being treated for cancer. Staying active and having a sense of humor help, she says. “It’s really important to be around people who understand you’ve gone through treatment.”
1 Tannock IF, Ahles TA, Ganz PA, Van Dam FS. Cognitive impairment associated with chemotherapy for cancer: Report of a workshop. Journal of Clinical Oncology. 2004;22(11):2233-39.
2 Chemo Brain. American Cancer Society Web site. Available at:http://www.cancer.org/docroot/MBC/content/MBC_2_3x_Chemobrain.asp. Accessed June 22, 2008.
3 Abraham J, Haut MW, Moran MT, Filburn S, Lemiuex S, Kuwabara H. Adjuvant chemotherapy for breast cancer: Effects on cerebral white matter seen in diffusion tensor imaging. Clinical Breast Cancer. 2008;8(1):88-91.
4 Chemobrain: When Cancer Treatment Disrupts Your Thinking and Memory. Mayo ClinicWeb site. Available at:http://www.mayoclinic.com/health/cancer-treatment/CA00044. Accessed June 22, 2008