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Doctor Doctor: Chemobrain — Are Those Foggy Feelings Real?

Network - Fall 2007


M. D. Anderson has one of the few dedicated neuropsychology services in a cancer center. One of the prime concerns of its chief, Christina Meyers, Ph.D., is the cognitive dysfunction — known as “chemobrain” — that many patients experience as a result of cancer and cancer treatment. Along with her colleague Tracy Veramonti, Ph.D., who spearheads the Management and Interventions for Neurocognitive Dysfunction (MIND) Clinic, she answers questions about this important side effect and recommends coping mechanisms for cancer survivors.

What is chemobrain?

“Chemobrain” or “chemofog” is a term coined by patients to describe changes in cognitive or thinking abilities that can occur in people diagnosed with cancer. 

When was it identified as a “real” side effect?

Cancer patients have always known that their cognitive function is less efficient during cancer treatment, although in the past it may have been attributed to other causes, such as stress or depression. However, there have been a number of studies over the past decade documenting this as a real effect of the disease and treatment on brain function.

In the beginning, how were patients studied to determine if they had chemobrain?

Christina Meyers, Ph.D.

In some cases, patients were simply asked to subjectively rate their experience of cognitive symptoms on questionnaires or checklists. However, this practice is somewhat problematic and more recent studies yielding much more sophisticated data have incorporated sensitive and reliable tests to capture the cognitive symptoms associated with cancer and cancer treatment. 

These tests of cognitive functioning (often referred to as “neuropsychological tests”) are non-invasive means of capturing changes in a person’s thinking abilities. While a CT scan or MRI can show the structure of the brain, neuropsychological tests determine how well the brain is working when performing certain types of tasks, like remembering. Most neuropsychological tests involve responding verbally to test questions or working with stimulus materials on a table.   

Typically, patients undergoing neuropsychological testing are administered a battery of measures that examine attention, speed of thinking, ability to multi-task, efficiency of learning and memory retrieval, and other cognitive functions. In addition, a comprehensive evaluation includes assessment of emotional function and symptoms that can compromise a patient’s quality of life. In this way, the possible reason(s) behind why a person complains of a symptom such as “forgetfulness” can be understood, and specific treatment recommendations can be tailored to the problems at hand. 

What are its causes?

While cognitive symptoms are often expected when cancer directly affects the brain, research has documented that patients with systemic malignancies — for example, breast cancer, lung cancer or leukemia — may have cognitive symptoms even before treatment begins. Additionally, many aggressive cancer treatments, such as chemotherapies, are not highly specific and place normal cells and organs, including the brain, at risk. This may lead to a worsening of cognitive symptoms or an emergence of new symptoms after treatment begins. Moreover, patients with cancer may be susceptible to cognitive symptoms secondary to side effects of medications commonly used in addition to primary therapies, such as steroids or anticonvulsants, or secondary to medical complications, such as anemia. 

What are its symptoms?

Patients may describe difficulties recalling something they were told previously; forgetting or confusing details of recent events; forgetting to pass on a message; misplacing things in their home or office; or confusing dates and times of appointments. Other common patient complaints include word-finding difficulties, which are often described by patients as the experience of “forgetting” words or names of people and/or locations, although they eventually remember.

In addition to these difficulties, patients may describe inefficiencies in attention, including trouble remaining focused on one task for any length of time or have a problem dividing attention between multiple tasks at the same time, known as “multi-tasking.” They often describe problems with organization and keeping up with conversations or occupational responsibilities due to slowed mental processing speed. They may describe their life in general as “no longer being on auto-pilot.”

How long do the symptoms last?

Jeffrey Wefel, Ph.D., and Christina Meyers, Ph.D., of the Neuropsychology Service, together with colleagues in the departments of Breast Medical Oncology and Gastrointestinal Medical Oncology at M. D. Anderson, published the first research trial evaluating cognitive functioning in women undergoing treatment for breast cancer that incorporated cognitive assessments prior to the start of chemotherapy and upon the completion of chemotherapy.

Before the start of chemotherapy, about one-third of study participants exhibited cognitive impairment, as documented on objective measures of neuropsychological functioning measuring skills, such as attention, mental processing speed, memory, problem solving and motor speed.

At approximately three weeks after chemotherapy was started, 61% of patients showed a decline relative to their pretreatment scores and generally reported greater difficulty in maintaining their ability to work. One year after treatment was completed, approximately one-half of those patients who experienced declines in cognitive functioning during treatment showed improvement, while 50% did not, so the symptoms may last longer than anyone previously realized. The patients who did get better reported that their ability to perform work-related activities also improved. 

As the above research study documented, sometimes cognitive symptoms may persist after treatment is completed, and even after patients are rendered “cured” or “disease-free.” In these cases, individuals may be embarrassed and even ashamed — feeling they should be thankful that their battle with cancer is over, instead of being distressed by a “memory problem” in the context of an otherwise successful outcome. Unfortunately, cognitive symptoms can lead to emotional distress and impede a patient’s ability to successfully meet scholastic, vocational and/or household goals.

Are there current studies on chemobrain? If so, what are they?

There are a number of longitudinal studies being performed in various institutions. The main goal now is to understand how these symptoms come about. Therefore, the studies increasingly include blood analysis, brain imaging and genetic testing to try to understand the reasons why some people develop “chemobrain” and others do not.

What coping mechanisms can you recommend to patients experiencing chemobrain?

As part of a multidisciplinary assessment, which includes medical evaluation and laboratory studies to rule out potentially reversible causes of cognitive problems, patients with cognitive symptoms may be referred to a neuropsychologist for evaluation and intervention. A neuropsychologist is a psychologist who has received specialty training in the science of brain-behavior relationships, including the study of brain anatomy and functioning, brain injury and disease. In a cancer setting, a neuropsychologist provides quantitative assessment of the cognitive and emotional symptoms that arise as a consequence of cancer, cancer treatment and/or co-existing neurologic or psychological problems. 

If a learning and memory problem is documented through testing, a neuropsychologist can work with the patient to identify strategies to minimize the impact of the problem on daily life. One frequent intervention involves development and implementation of memory aids, such as day planners, memory notebooks or medication reminder systems. Memory aids are often specifically tailored to meet patients’ individual needs, considering their routine activities, vulnerabilities to everyday memory symptoms, and pattern of cognitive strengths and weaknesses determined through neuropsychological evaluation. 

Sometimes, memory difficulties may be associated with underlying problems in attention or distractibility. In these cases, patients may be educated in ways to minimize distractions in work and social environments. Fatigue and generalized cognitive slowing also may contribute to or increase cognitive symptoms. In either case, patients may be referred to a physician for consideration of stimulant medications that can be beneficial. Managing depression and anxiety, if they occur, is also crucial. Emotional distress can further contribute to cognitive symptoms. Patients may be referred to a psychiatrist for consultation regarding medications for their distress and/or to a psychologist for psychotherapy.


© 2014 The University of Texas MD Anderson Cancer Center