A new study from Washington University School of Medicine in St. Louis has found a strong association between high levels of physical activity and the ability to maintain cognitive function among breast cancer patients treated with chemotherapy.
The research lays the groundwork for future clinical trials aimed at investigating whether moderate to vigorous exercise can ward off what is commonly referred to as “chemo brain,” a decline in cognitive function that many breast cancer patients experience.
The study appears online in the Journal of Clinical Oncology. In addition to Washington University School of Medicine in St. Louis, researchers at the University of Rochester Medical Center in Rochester, NY, and the National Cancer Institute of the National Institutes of Health (NIH), participated in the study.
The researchers analyzed data from a national sample of 580 breast cancer patients and 363 cancer-free participants, who acted as controls. The scientists measured physical activity as reported by patients on a questionnaire taken before, immediately after and six months after chemotherapy. At the same three times, the researchers also assessed four different measures of cognitive function.
At the beginning of the study, about 33% of the cancer patients met physical activity guidelines set by the U.S. Department of Health and Human Services. The guidelines recommend at least 150 minutes of moderate to vigorous physical activity per week. During chemotherapy, the percentage of patients meeting the guidelines dropped to 21% and then rebounded to 37% six months after treatment ended. The proportion of cancer-free participants meeting the weekly minimum of 150 minutes of moderate to vigorous physical activity hovered around 40% at all three time points.
The four assessments of cognition included two measures of how individuals perceive their own cognition; a test of visual memory; and a test of sustained attention. Inactive patients showed what is classified as a moderate reduction in perceived cognitive function, which is considered clinically meaningful. On all of the assessments, patients who had met the physical activity guidelines before and after chemotherapy consistently outperformed patients who had never met the guidelines. The cancer-free study participants performed similarly on all of the assessments, regardless of whether they had met the physical activity guidelines.
Importantly, breast cancer patients who had met the physical activity guidelines before chemotherapy ended up performing similarly to active and inactive healthy participants on the memory and attention tests. While objective measures of memory and attention indicated that physically active cancer patients had performed about as well as cancer-free participants, the physically active patients still perceived a significant decline in cognition, especially during chemotherapy. However, their perceived decline was not as great as that of the inactive patients. The researchers speculate that the self-reported measures of cognition may be capturing other common problems associated with chemotherapy, such as anxiety, fatigue or depression.