Study: Physical Activity Associated With Better Cognition in Breast Cancer Patients

This research lays the foundation for future clinical trials aimed at investigating whether moderate to vigorous exercise can minimize “chemo brain,” which is a decline in cognitive function many patients with breast cancer experience.

There is a strong connection found between high levels of physical activity and the ability to maintain cognitive function among patients with breast cancer treated with chemotherapy, according to a new study from Washington University School of Medicine in St. Louis.

This research lays the foundation for future clinical trials aimed at investigating whether moderate to vigorous exercise can minimize “chemo brain,” which is a decline in cognitive function many patients with breast cancer experience.

“Cognitive decline related to cancer treatment is a growing clinical concern,” said first author Elizabeth A. Salerno, PhD, an assistant professor of surgery in the Division of Public Health Sciences at Washington University, in a press release. “Some patients with cancer experience memory lapses, difficulty concentrating or trouble finding the right word to finish a sentence. Knowing the detrimental effects of chemotherapy on cognitive function, we wanted to understand the dynamic relationships between physical activity and cognition before, during and after chemotherapy to hopefully inform early, cost-effective prevention strategies to promote health in these patients. Our findings suggest that maintaining higher levels of physical activity may indeed be important for protecting cognition in patients with breast cancer undergoing chemotherapy.”

The research team noted that their observational study cannot demonstrate that physical activity fully protects against chemotherapy-related cognitive decline, since it is possible that physically active people have other characteristics, independent of exercise, that may protect cognition. However, the study sets the stage for clinical trials investigating whether physical activity interventions before and during chemotherapy can ward off treatment-related cognitive decline.

“Physical activity is a complex behavior,” Salerno said in a press release. “So, it will be important to test whether we can intervene with physical activity during a specific time window, such as during chemotherapy, and protect cognitive function in patients of all activity levels.”

Data were analyzed from a national sample of 580 patients with breast cancer and 363 cancer-free participants who acted as controls. The team then measured physical activity as reported by patients on a questionnaire taken before, immediately after, and 6 months after chemotherapy. At the same 3 times, the researchers assessed 4 different measures of cognitive function.

At the start of the study, approximately 33% of the patients with cancer met physical activity guidelines set by the US Department of Health and Human Services. The guidelines recommend at least 150 minutes of moderate to vigorous physical activity per week. During chemotherapy, patients meeting the guidelines dropped to 21% and rebounded to 37% in the 6 months after treatment ended. Further, the proportion of cancer-free participants meeting the weekly minimum of 150 minutes of moderate to vigorous physical activity hovered around 40% at all 3 time points, according to the study authors.

“Despite this recovery to pre-chemotherapy physical activity levels, a majority of patients remained insufficiently active,” Salerno said in a press release. “As we consider the design of future physical activity interventions during chemotherapy, it will be important to understand what may be driving this rebound, whether it be improved health status now that chemotherapy is over or renewed motivation toward healthy aging during survivorship.”

In the 4 assessments of cognition, 2 measures of how individuals perceive their own cognition were included: 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.

Patients who had met the physical activity guidelines before and after chemotherapy consistently outperformed patients who had never met the guidelines on all of the assessments. Additionally, the cancer-free study participants performed similarly on all of the assessments, regardless of whether they had met the physical activity guidelines.

Patients with breast cancer 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. Although objective measures of memory and attention indicated that physically active patients with cancer had performed about as well as cancer-free participants, the physically active patients still perceived a significant decline in cognition, specifically during chemotherapy.

The perceived decline was not as great as that of the inactive patients, in whom 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.

“Patients who were consistently meeting physical activity guidelines during chemotherapy not only had better cognitive recovery after chemotherapy completion, they also did not demonstrate clinically meaningful perceived cognitive decline, meaning that they did not report a large perceived cognitive change,” said senior author Michelle C. Janelsins, PhD, an associate professor at the University of Rochester Medical Center and Wilmot Cancer Institute in a press release. “By assessment with our objective cognitive measures, patients who were meeting physical activity guidelines prior to chemotherapy had better cognitive function scores following chemotherapy and looked cognitively similar to people who didn’t have cancer.”

Salerno added that these findings contribute to the growing body of evidence highlighting the importance of promoting physical activity as early as possible across the continuum of cancer care.

REFERENCE

Physical activity associated with better cognition in breast cancer patients. Washington University School of Medicine in St. Louis. August 18, 2021. Accessed August 20, 2021. https://medicine.wustl.edu/news/physical-activity-associated-with-better-cognition-in-breast-cancer-patients/