Cancer, Keeping Active, and the Mind

Physical illness can sideline an exercise routine. And cancer, whose treatment can result in side effects like fatigue and even lymphedema (the buildup of lymphatic fluid in tissues), can make one reluctant to get moving or wary about continuing or initiating physical activity. In the past, cancer treatment-related fatigue was addressed with recommendations to rest, but, more recently, suggestions to engage in physical activity stem from research that indicates that it can be engaged in safely and can maintain vitality.^1,2 Now exercise is being investigated as a means to boost mental capacities in cancer patients.

Cognitive changes following cancer chemotherapy, sometimes referred to as “chemobrain” or “chemofog,” can affect multiple types of mental abilities, including retaining information in memory, the speed of processing information, verbal and motor skills, and spatial ability. Importantly, these, in turn, can affect quality of life, relationships, and job functioning.³ Because physical activity has shown promise in improving the cognitive functioning of older adults, a team of researchers has set out to investigate if aerobic exercise shows promise as a means to combat the cognitive difficulties experienced by a small sample of breast cancer survivors.⁴

Nineteen women experiencing cancer treatment-related cognitive changes who had completed their treatment three months to three years prior and were physically capable of exercise were recruited. Their difficulties included forgetting things they had been told earlier in the day, having trouble concentrating, not being able to finish a conversation or reading an article, not competing tasks, or having trouble thinking through or planning things such as errands; they only needed to report experiencing one of these difficulties to qualify for the study. The aerobic exercise intervention (delivered to 10 of the women) consisted of 24 weeks of moderate-to-vigorous exercise. Two 45-minute sessions were conducted in a research gym and two additional 30-minute sessions, doing activities such as walking, were done at home each week. The control group (nine women) engaged in their usual lifestyle practices for the duration of the study, but were offered a 12-week exercise program at the end.

The study sample was, on average, 52 years old, overweight, and not physically fit. Nonetheless, the treatment group had good adherence to the exercise program and increased their aerobic fitness significantly, indicating that they received the full “dose” of the intervention that had been intended. There was also a clinically meaningful improvement in levels of fatigue, in that ratings moved from what would be considered a higher score to a lower score on a validated scale, but this was not statistically significant. There were, however, no significant differences between the exercise and control groups in the perceived impact of cognitive dysfunction on quality of life and there was only one significant difference in nine objective neuropsychological tests of verbal fluency and motor processing speed. There were some suggestive findings from a proportion of the sample that agreed to undergo magnetic resonance imaging. While participants engaged in a task that involved executive functioning, their brains were activating in relevant areas in ways that were more efficient, perhaps indicating that less effort was needed to maintain the same level of task performance.

Although these preliminary findings are far from those that could be used to recommend physical activity to mitigate cancer-related cognitive change, the authors still believe it could hold promise. They offered suggestions for future research, namely exploring what a maximally effective dose of exercise might be and perhaps administering it earlier, considering different types of cognitive tests that are sufficiently sensitive to self-reported cognitive complaints following breast cancer, and using a more rigorous screening tool to determine compromised cognitive functioning.