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HomeOncologyExercise may alleviate ‘chemo brain’ in breast cancer — Washington University study

Exercise may alleviate ‘chemo brain’ in breast cancer — Washington University study

Regular exercise may help lessen “chemo brain” among women being treated for breast cancer, according to a large-scale study of the associations between physical activity, chemotherapy and cognition. The study, which involved more than 500 women with breast cancer, found that those who were the most active before, during or after their treatment were the least likely to develop the memory decline and foggy thinking that characterise chemo brain.

According to The New York Times, the study does not pinpoint precisely how exercise may protect the brain during chemotherapy, but does suggest even small amounts of activity, such as a half-hour walk when possible, could make a difference in cancer patients’ ability to think and remember as they move toward recovery.

Cognitive problems are nearly universal among women undergoing chemotherapy for breast cancer. “Most patients will experience some degree of cognitive decline” during or after their treatment,” said Elizabeth Salerno, an assistant professor of surgery and public health at Washington University School of Medicine in St Louis, who led the study.

In an earlier study written by many of her collaborators, researchers found that women’s ability to concentrate and remember worsened significantly after they began chemotherapy, and the falloff lingered or even accelerated through the six months after their treatment ended.

The causes of this so-called chemo brain remain somewhat mysterious, Salerno said, but probably involve a complex interplay between physical and psychological side effects from the disease and treatment. Chemotherapy drugs may directly undermine the operations of certain brain cells, for instance, or cause inflammation throughout the brain. Women with breast cancer also often struggle with fatigue, depression or anxiety during their treatment, which likewise can influence the ability to think and remember.

Meanwhile, experts increasingly recommend exercise for people with cancer of almost any type, including breast cancer, since it typically combats certain of the more-debilitating side effects of treatment, such as fatigue and muscle loss. Perhaps even more important, in high-risk breast cancer patients, exercise is linked to significantly lower risks of recurrence and longer life spans.

But little has been known about whether being active might also alter the severity of chemo brain, the New York Times reports. Past research into moving and thinking during breast cancer treatment has been mostly small in scale or centered on physical activity during chemotherapy, when few women, understandably, manage to get much exercise.

So, for the latest study, which was published in August in the Journal of Clinical Oncology, Salerno and her colleagues decided to reanalyse the data from the earlier study of cognitive decline in women undergoing chemotherapy. This time, they focused on how much the women moved before and after, as well as during, their chemo, and the relationship between being active and their ability to think clearly. (The original research was designed and led by Michelle C. Janelsins, an associate professor of surgery at the University of Rochester Medical Center in Rochester, New York, who also was an author of this latest study.)

In the original study, 580 women with a diagnosis of Stage I to Stage IIIC breast cancer, meaning malignancies that were contained in or near the breast, completed questionnaires and tests about a week before starting chemotherapy. One form asked them to recall how much time they spent recently in any physical activity, whether vacuuming, gardening, walking or more-rigorous sports like jogging. Separate questionnaires asked how they felt, right at that moment, about their ability to think and remember.

Finally, several computer tests measured their visual memory, which is the vital ability to remember what something looks like, as well as their attention.

The women repeated these forms and tests during the final week of their chemotherapy and again, six months later. Separately, 363 women without breast cancer completed the same forms and tests on about the same schedule, to serve as a control. Then the researchers compared activity levels and cognition. Over all, the women with breast cancer were relatively inactive before starting chemotherapy. Only a third of them met standard exercise guidelines, which call for at least 150 minutes a week of moderate exercise, such as a brisk, half-hour walk most days. The percentage of patients meeting these guidelines dropped to 21% near the end of chemotherapy, but rebounded to 37% six months later. For the control group, it hovered at about 40% throughout the experiment.

Women’s symptoms of chemo brain generally paralleled their activity levels. Those few patients who met the guidelines before and throughout their treatment showed little cognitive decline at all. Their results on the computer tests before, during and after their chemotherapy were comparable to those for the control group (although some of the patients reported feeling less sharp). Perhaps most compelling, if women with cancer started out active, meeting the exercise guidelines before chemo, they tended to score higher on the cognitive tests six months later than woman who had been inactive from the start, even if they stopped moving much during treatment.

These findings suggest that aiming to meet exercise guidelines before beginning chemotherapy might be a worthwhile goal, Salerno said, although this study does not tell us how much or how little exercise would be ideal, or how long before chemo might be the best moment to start exercising. It also is observational, so does not show exercise causes thinking to be unaffected by chemo, only that women who move also experience less chemo brain.

Above all, these results are not meant to worry or badger women who feel too fatigued or ill or overwhelmed to exercise in the midst of chemotherapy. “It is important for patients to show themselves grace,” Salerno said. Rest as much as you need to. When you are able, perhaps walk around the block or up a single flight of stairs, she said. One of the most encouraging and unexpected aspects of the study for her, she said, was that more women reported exercising six months after chemotherapy than before treatment began. “They seemed to want to be moving again. There’s something beautiful about that.”

Study details

Physical Activity Patterns and Relationships With Cognitive Function in Patients With Breast Cancer Before, During, and After Chemotherapy in a Prospective, Nationwide Study

Elizabeth Salerno, Eva Culakova, Amber Kleckner, Charles Heckler, Po-Ju Lin, Charles  Matthews, Alison Conlin, Lora Weiselberg,Jerry Mitchell, Karen Mustian, and Michelle  Janelsins

Published in Journal of Clinical Oncology on 18 August 2021


Physical activity (PA) is a promising intervention for cancer-related cognitive decline, yet research assessing its use during chemotherapy is limited. This study evaluated patterns of PA before, during, and after chemotherapy in patients with breast cancer and the association between PA and cognitive function.

In a nationwide, prospective cohort study, we assessed PA (Aerobics Center Longitudinal Study PA measure) and perceived and objectively measured cognitive functioning (Functional Assessment of Cancer Therapy–Cognitive, Delayed Match to Sample, and Rapid Visual Processing measures) at prechemotherapy (T1), postchemotherapy (T2), and six months postchemotherapy (T3) in patients with breast cancer and cancer-free, age-matched controls at equivalent time points. Longitudinal linear mixed-effects models (LMMs) characterised PA changes over time between patients and controls, adjusting for demographic and clinical factors. LMMs further estimated the role of prechemotherapy PA and changes in PA during chemotherapy on cognitive changes over time.

Patients with stage I-IIIC breast cancer (n = 580; age M [standard deviation] = 53.4 [10.6] years) and controls (n = 363; age M [standard deviation] = 52.6 [10.3] years) were included. One third of patients met national PA guidelines at T1, dropping to 21% at T2 before rising to 37% at T3. LMMs revealed declines in PA from T1 to T2 in patients compared with controls (all P < .001). Patients meeting guidelines at T1 demonstrated better cognitive scores over time on the Functional Assessment of Cancer Therapy–Cognitive and Rapid Visual Processing (all P < .05), with similar patterns of objectively-measured cognitive function as controls. In patients, greater moderate-to-vigorous PA at the previous time point was significantly associated with better cognitive trajectories (all P < .05), and adherence to PA guidelines throughout chemotherapy was associated with better self-reported cognition (P < .01).

This nationwide study demonstrates that PA maintenance before and during chemotherapy is associated with better cognitive function immediately and six months after chemotherapy completion.

Earlier study

Study details

Longitudinal Trajectory and Characterization of Cancer-Related Cognitive Impairment in a Nationwide Cohort Study

Michelle Janelsins, Charles E. Heckler, Luke Peppone, Tim Ahles, Supriya Mohile, Karen  Mustian, Oxana Palesh, Ann  O’Mara, Lori  Minasian, Annalynn Williams, Allison Magnuson, Jodi Geer, Shaker Dakhil, Judith Hopkins, and Gary  Morrow

Published in Journal of Oncology on 21 September 2018

Cancer-related cognitive impairment (CRCI) is an important clinical problem in patients with breast cancer receiving chemotherapy. Nationwide longitudinal studies are needed to understand the trajectory and severity of CRCI in specific cognitive domains.

Patients and Methods
The overall objective of this nationwide, prospective, observational study conducted within the National Cancer Institute Community Clinical Oncology Research Program was to assess trajectories in specific cognitive domains in patients with breast cancer (stage I-IIIC) receiving chemotherapy, from pre- (A1) to postchemotherapy (A2) and from prechemotherapy to 6 months postchemotherapy (A3); controls were assessed at the same time-equivalent points. The primary aim assessed visual memory using the Cambridge Neuropsychological Test Automated Battery Delayed Match to Sample test by longitudinal mixed models including A1, A2, and A3 and adjusting for age, education, race, cognitive reserve score, and baseline anxiety and depressive symptoms. We also assessed trajectories of CRCI in other aspects of memory as well as in attention and executive function with computerised, paper-based, and telephone-based cognitive tests.

In total, 580 patients with breast cancer (mean age, 53.4 years) and 363 controls (mean age, 52.6 years) were assessed. On the Delayed Match to Sample test, the longitudinal mixed model results revealed a significant group-by-time effect (P < .005); patients declined over time from prechemotherapy (A1) to 6 months postchemotherapy (A3; P = .005), but controls did not change (P = .426). The group difference between patients and controls was also significant, revealing declines in patients but not controls (P = .017). Several other models of computerised, standard, and telephone tests indicated significantly worse performance by patients compared with controls from pre- to postchemotherapy and from prechemotherapy to 6 months postchemotherapy.

This nationwide study showed CRCI in patients with breast cancer affects multiple cognitive domains for at least 6 months postchemotherapy.


The New York Times article – Exercise may alleviate ‘chemo’ brain (Restricted access)


Journal of Clinical Oncology abstract – Physical Activity Patterns and Relationships With Cognitive Function in Patients With Breast Cancer Before, During, and After Chemotherapy in a Prospective, Nationwide Study (Open access)


Journal of Clinical Oncology article – Longitudinal Trajectory and Characterization of Cancer-Related Cognitive Impairment in a Nationwide Cohort Study (Open access)


See more from MedicalBrief archives:


'Chemo brain' is real – study


Exercise improves cognitive ability in breast cancer survivors


American College of Sports Medicine: Exercise guidelines for cancer survivors



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