by Dr. Karen Syrjala, co-director of the Survivorship Program and director of the Biobehavioral Sciences group, Fred Hutchinson Cancer Research Center
We anticipate the loss of certain things in the process of cancer treatment—hair, perhaps, or our sense of invincibility—but losing one’s mental edge is often unanticipated and particularly disconcerting.
Mild cognitive impairment following cancer treatment is one of the most common symptoms reported by cancer survivors. This troubling deterioration in cognitive function is commonly called “chemobrain” or “chemofog,” though the names are somewhat misleading since chemotherapy may not be its sole cause.
The condition encompasses a range of problems much like those linked to aging. Even as they are feeling better physically, cancer survivors often cannot remember where they put their keys or recall a short list of things they had planned to purchase. Some say they are easily distracted or lose the ability to calculate in their heads. Survivors report diminished quality of life and daily functioning, and the impairment comes at economic, emotional and interpersonal costs.
But a growing body of research on chemobrain in the last decade has better defined the condition, and studies are beginning to lift the fog and reduce some quality-of-life impacts that can accompany the condition.
The prevalence of chemobrain is hard to pin down. Estimates of cancer patients affected range from about 14 percent to as high as 85 percent. While researchers agree that its occurrence is much more dependent on the type of treatment than on the specific type of cancer, little is known about who is most likely to suffer a long-term deficit or how to guard against it. If you’ve had high-dose chemotherapy, we know that you’re highly likely to have deficits across the board in the short term. We can see changes when we do imaging of the brain. Treatment hits people hard.
In our research, the most common problem we hear is difficulty finding words or names—the tip-of-the-tongue experiences. You see a good friend in the grocery store and you know their name as well as you know your own but your brain can’t seem to make the right connections to retrieve the name. People also frequently report short-term memory issues and difficulties with fine-motor and hand-eye coordination.
While most people recover, the process may be slower than they wish. There may be some areas that don’t recover 100 percent, but research shows that the majority of survivors do function well in the world, even those who may have to adapt to chemobrain. About 30 percent of patients have long-term cognitive effects that may impair their ability to manage the demanding world we live in.
Because of the widely divergent patient experiences, studying the cognitive consequences of cancer treatment has been problematic. In some cases, this has led to a disconnect between patient experiences and attention to the issue. Even though patients have been talking about these problems since the 1970s, it’s only in the last decade that systematic research has been conducted.
The number of studies investigating post-treatment cognitive impairment has significantly increased in the past 10 years. As science does a better job defining the difficulties stemming from chemobrain, many in the medical community who were once skeptical have come to accept its existence.
A series of studies that combined neuropsychological testing with sophisticated brain imaging and molecular analyses allowed researchers to better define what was previously only loosely described through anecdotal evidence. And some research studies are beginning to yield new strategies to mitigate some of the quality-of-life impacts that can accompany cognitive decline after cancer therapy.
In one study of breast cancer survivors with persistent memory problems, brain scans showed that the women who had received chemotherapy had a lower resting brain metabolism. While taking a memory test, the chemo-treated patients used a larger portion of their frontal cortexes than the untreated women. That meant that the treated women were working their brains harder to perform the task. Other imaging studies have found similar results.
In 2004, we published findings from a first-ever, large-scale neuropsychological study that assessed stem-cell transplant patients before and after treatment.
We found significant reduction in cognitive function on all tests 80 days post-transplant. However, performance returned to pre-transplantation levels at one year on all measures except for grip strength and motor coordination. In 2011, we are reporting on the same group five years after treatment and we have found no difference between survivors and the regular population in executive function—high-level, multi-tasking abilities. However, tasks such as information processing speed, memory and motor coordination remained lower in five-year survivors than the regular population who had not received cancer treatment.
Interestingly, my research team found a higher percentage of patients than expected scored below average on tests for verbal fluency and memory even prior to their treatment. Other baseline studies of patients after diagnosis but before treatment have found this, too. The results suggest that blaming cognitive problems solely on chemotherapy is too limiting.
Researchers believe other factors associated with cancer, such as elevated levels of inflammatory cytokines—cell proteins that help regulate the intensity of the body’s immune response—and DNA damage, may contribute to below-average baseline cognition. Clearly some people are more vulnerable to this damage than others.
One of the central puzzles of chemobrain is that many of the symptoms can occur for reasons other than cancer treatment. Coexisting factors like age, fatigue, stress, as well as other medications, make it difficult to tease apart the driving contributors. Cognitive difficulties are also core symptoms for diagnosing depression and anxiety.
Other researchers are turning their attention to mitigating cognitive problems. Some studies have shown modest improvement in memory problems among cancer survivors using a mild stimulant medication. Efforts are also being aimed at cognitive rehabilitation, coping strategies and adoption of healthy habits like exercise to improve working memory. The Survivorship Program can help direct sufferers to cognitive rehabilitation and fitness programs.
Since numerous health and behavioral factors can affect optimal cognitive functioning, the first step for concerned cancer survivors is always to get an evaluation to determine if there are measurable deficits. Medications, nutrition and sleep patterns should be reviewed. Stress level and mood disorders should be assessed and, if necessary, treated. Depending on the severity of cognitive dysfunction, treatment may range from intervention by a work coach to the implementation of aids such as a notebook or electronic device. We also teach people to adapt and adjust expectations and scheduling so they do their most intensive brain work when they’re most alert.
As the number of survivors continues to grow, cognitive deficits will become a critical quality-of-life concern for millions of cancer patients. The best news is that we’ve made such progress in saving people from cancer that we can worry about these things now. These concerns are clearly important and it’s essential for us to keep applying our scientific tools to the problem.
Q: What can I do to improve my mental fogginess?
Memory problems are quite common after cancer treatment. Many survivors find these struggles improve over time; in the meantime, try some of these strategies to cope with post-cancer cognitive difficulties: