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Scientists are testing aerobic exercise’s effects on people who have received chemotherapy. Guido Mieth/Getty Images
  • Up to 75% of people who undergo chemotherapy for cancer experience “brain fog” or “chemo brain.”
  • Past studies show there are some ways to potentially treat chemo-related brain fog, including physical activity.
  • Researchers have found that women undergoing chemotherapy for breast cancer, who also began an aerobic exercise program at the same time, self-reported significant improvements in both cognitive function and quality of life compared with women who did not.

One of the most common side effects of chemotherapy is “brain fog” — an experience where a person may have trouble remembering things and thinking clearly.

Also known as “chemo brain,” past research shows that up to 75% of people who receive chemotherapy experience this type of cognitive impairment.

Previous studies show there are some ways to potentially treat chemo-related brain fog, such as medications, mindfulness-based interventions, and physical activity.

“Most people have likely experienced some form of brain fog, where thinking clearly, processing information, or staying focused feels difficult,” Jennifer Brunet, PhD, full professor in the School of Human Kinetics at the University of Ottawa explained to Medical News Today. “This is often amplified in women undergoing chemotherapy for breast cancer, with research showing that around 75% experience brain fog symptoms such as confusion, forgetfulness, slow thinking, and trouble focusing or concentrating.”

Brunet is the lead author of a new study recently published in the journal CANCER, that found women undergoing chemotherapy for breast cancer — who also began an aerobic exercise program at the same time — self-reported significant improvements in both cognitive function and quality of life compared with women who did not.

Brain fog after chemotherapy

“There is variation in how long women experience brain fog, though for many, it persists for several months or even years after treatment, significantly impacting daily life and mental health. Currently, there is no treatment to prevent or reduce chemotherapy-induced brain fog, leaving healthcare providers with limited options to support their patients. This is why it is critical for researchers to continue exploring new ways to treat brain fog and limit its impact on women treated with chemotherapy for breast cancer.”
— Jennifer Brunet, PhD

For this study — called the Aerobic exercise and CogniTIVe functioning in women with breAsT cancEr (ACTIVATE) trial — researchers recruited 57 women from Ottawa and Vancouver, Canada, diagnosed with stage I-III breast cancer.

All study participants participated in 12 to 24 weeks of aerobic exercise — 28 participants started the exercise program at the same time as initiating chemotherapy, while the other 29 started the exercise program after completing chemo.

“Lifestyle changes, such as aerobic exercise, are often recommended to older adults and individuals with mild cognitive impairment to help reduce brain fog and its impact. Research shows that aerobic exercise can enhance both mental and physical health and may also help boost women’s cognitive function; however, strong evidence for the latter is missing,” Brunet said.

At the study’s conclusion, Brunet and her team found that women who started their aerobic exercise program at the same time they started chemotherapy self-reported better cognitive functioning and felt that their mental abilities improved compared to those who started exercising after their chemo was over.

However, researchers did point out that neuropsychological testing showed similar cognitive performance in both groups.

“Healthcare providers need to recognize that brain fog is a common and burdensome side effect of chemotherapy in women with breast cancer. While exercising may not completely eliminate brain fog, it can address some of the underlying causes,” Brunet said.

“Healthcare providers can encourage their patients to incorporate more aerobic exercise into their daily routine during and after chemotherapy as a way to manage symptoms. By discussing the potential cognitive benefits of exercise alongside the physical and mental health benefits of exercise, they can offer their patients a proactive strategy to support their recovery and enhance their quality of life.”
— Jennifer Brunet, PhD

After reviewing this research, Bhavana Pathak, MD, a board certified hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA, told MNT she was extremely pleased that this study was conducted as there are limited standards of care for treatment of cognitive impairment due to chemo.

“Aerobic activity has been shown to improve cognitive function in other disease states and I appreciate the authors’ reflection on the fact that the patient reported outcomes were superior in the exercise intervention group,” Pathak continued.

“This addresses the quality-of-life aspects of our treatment. Without a reasonable means to intervene, the therapy we give — while (it) could keep you alive — can take away a life worth living, without the means to articulate, adapt, and engineer your life,” she said.

“This type of research speaks to the privilege and challenge both patients and physicians have — designing and choosing treatments that have an impact on the rest of their lives. I would like to see secondary outcome measures like patient outcomes at the time of surgery (ie pathologic complete response), disease free survival, based on this data on the impact of cognition and quality of life,” she added.

MNT also spoke with Diana Garrett, PT, DPT, FAAOMPT, CLT, CSCS, a board certified orthopedic clinical specialist and program director of physical therapy services of the Women’s Health & Wellness Institute at Providence Saint John’s Health Center in Santa Monica, CA, about this study.

“We have known for a long time about the benefits of exercise on cognitive function, in addition to all the cardiovascular, strength, bone health, and mental health benefits that arise from exercising,” Garrett said.

“It was interesting to see that the benefits of exercise were obtained in both groups regardless of when the physical activity occurred during or after chemotherapy treatment. This reiterates the importance of maintaining movement and physical activity,” she said.

“Cognitive dysfunction secondary to chemotherapy can have a significant impact on a person’s daily life. Exercise increases perfusion and overall blood circulation to the brain, in addition to increased neuroplasticity where there is development of synaptic connections and neuronal networks.”
— Diana Garrett, PT, DPT, FAAOMPT, CLT, CSCS

“It is important to continue to investigate ways to mitigate the effects of chemotherapy in order to enhance overall survivorship,” she added.