Exercise After Breast Cancer Surgery Clears 'Brain Fog'

Kristin Jenkins

September 25, 2017

Many women with breast cancer experience problems with memory, concentration, and information processing that can last for years after treatment and that can potentially take a toll on independent living.

Now, one of the first randomized, controlled intervention studies to examine the effects of moderate to vigorous physical activity on cognition in a cancer population shows that increased aerobic physical activity within 2 years of surgery tripled cognitive processing scores in breast cancer survivors on both objective and self-rated tests.

Processing speed, as determined by scores on the Oral Symbol Digit subscale, showed differential improvement in women in the exercise group when compared to those in the control group (b = 2.01; P <.05), say Sheri J. Hartman, PhD, of the University of California-San Diego Moores Cancer Center, in La Jolla, and colleagues in a report published online September 19 in Cancer. Of nine examined cognitive domains, however, significantly greater improvements were observed only with respect to processing speed in the exercise arm compared with the control arm, the study authors point out.

"This study provides preliminary support for the efficacy of increasing physical activity to improve processing speed and, potentially, self-reported cognition in breast cancer survivors," they write. "With the growing interest in testing the potential of physical activity to improve cognition in cancer survivors, this and other studies are likely to contribute to our ability to make recommendations to the growing number of cancer survivors on effective interventions to improve cognition."

Memory and Motion Study

The Memory and Motion Study demonstrates a clear association between the amount of exercise and the degree of improvement in objective and self-rated cognition scores, the authors report. A 15-minute increase in daily exercise resulted in an average 3.0-point increase on the Oral Symbol Digit score as well as a 10.2-point decrease in the standardized self-report Cognitive Concerns score.

Similarly, a 30-minute increase in daily exercise was associated with an average 0.84-point increase in the Fluid Composite score and an average 1.3-point increase in the Picture Sequence score. Overall, women in the exercise intervention program, who were previously sedentary, increased their amount of weekly physical activity by about 100 minutes.

The study also demonstrates that the amount of time that has elapsed since surgery makes a critical difference in the impact of exercise on cognition, the authors note. Women who had undergone surgery less than 2 years before the exercise intervention experienced a significantly greater improvement in Oral Symbol Digit score than control patients (exercise vs control, b = 4.00; P < .01). However, women who had undergone surgery more than 2 years before did not experience any cognitive benefits from exercise (b= -1.19; P = .40).

"This study supports the idea that exercise could be a way to help improve cognition among breast cancer survivors," said Dr Hartman, who is assistant professor in the Department of Family and Preventive Medicine at the University of California, San Diego, Moores Cancer Center, in a statement. "This is a preliminary study, but it appears that intervening closer to diagnosis may be important to having an impact, and this is the population we may need to target," she added. She noted that breast cancer survivors often report that their thinking processes have slowed following treatment.

Even for breast cancer patients who do not undergo chemotherapy, up to 75% experience a cognitive decline that reduces their information processing speed as well as memory and concentration. Because there is good evidence that exercise can improve cognition in older adults without cancer, the researchers were hopeful that exercise could do the same for breast cancer survivors, Dr Hartman told Medscape Medical News. "We were glad to see some evidence that it was," she said.

The average age of the breast cancer survivors in the study was 57 years, and participants had been diagnosed with breast cancer an average of 2.5 years prior to enrollment. Participants were predominantly non-Hispanic white college graduates; 61% had stage I breast cancer, 53% had received chemotherapy, and 70% were receiving an aromatase inhibitor or tamoxifen.

A total of 43 women were randomly allocated to a physical activity intervention program tailored to their unique interests and abilities; 44 were allocated to a control group that received information by email about women's health topics, healthy eating, stress reduction, and general brain health.

All wore an accelerometer for the first 7 days of the 12-week study and then again for the last 7 days. At baseline and at 12 weeks, cognition was measured objectively with the National Institutes of Health Cognitive Toolbox, and all patients self-reported cognitive abilities and problems using the Patient Reported Outcomes Measurement Information System scales.

Women in the exercise arm wore a Fitbit One activity tracker and were told to engage in at least 150 min of moderate to vigorous physical activity per week. After analyzing data on participants' activity levels, the researchers provided the women in the exercise group with feedback and support by telephone and email.

Clinicians can play an important role in helping breast cancer survivors banish brain fog and improve cognition by letting them know about the benefits of exercise, said Dr Hartman. "Many patients are not aware that increasing exercise could possibly help with [the] slowing in their thinking they are experiencing following their cancer treatments," she explained.

Knowing that finding motivation to exercise can be a problem for anyone, whether they have cancer or not, the authors suggest that by offering a supported exercise program, breast cancer survivors "are more likely to make difficult behavioral changes that lead to an increase in physical activity."

The next step with respect to research will be to conduct a longer study in a larger group of more diverse breast cancer survivors, Dr Hartman told Medscape. "We are interested in seeing if being active for longer results in benefits to more areas of cognition. We'd also like to test this with survivors of other types of cancer to know if increasing exercise could be helpful to more cancer survivors."

The study was funded by the National Cancer Institute of the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Cancer. Published online on September 19, 2017. Abstract

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