Relationhsip between Exercise and Cognitive functioning in Breast Cancer Survivors following Chemotherapy

BACKGROUND: A growing body of research suggests that individuals who undergo chemotherapy for treatment of cancer experience adverse changes in cognitive functioning as a side effect of treatment. While there is not yet a known remedy for such effects, exercise has shown to improve cognitive functioning in individuals within other clinical populations. Therefore, the purpose of this current study is to examine whether any relationships exist between self-reported post-chemotherapy exercise and cognitive functioning.

SUBJECTS: The sample consisted of sixty female breast cancer survivors between the ages of 38-71. All participants had been diagnosed with stage I, II, or III breast cancer and had completed chemotherapy between three months to two years prior to their study visit.

METHOD: Participants completed a self-report measure of post-chemotherapy exercise behavior and were administered a battery of neurocognitive tests to measure cognitive functioning. Subjects were categorized into one of three exercise groups based on their total exercise score (LSI): sedentary (LSI < 14), moderately active (LSI = 14-23), or active (LSI > 24). Mean scores on cognitive tests between exercise groups were compared to determine whether significant differences existed between groups both before and after controlling for IQ. Additionally, a hierarchical multiple regression was performed to determine how much of the variance in cognitive test scores could be explained by the following predictors: age, education, IQ, anxiety, depression, and exercise.

RESULTS: Only three test scores (CVLT, Digit Span Backward, and Digit Symbol Coding) showed significant differences between exercise groups. Before controlling for IQ, CVLT (F=7.40, p=.001) and Digit Span Backward (F=3.01, p=.057) displayed significant differences between groups. After controlling for IQ, CVLT (F=4.19, p=.012), Digit Span Backward (F=5.98, p=.004), and Coding (F=3.05, p=.055) displayed significant differences. Predictors explained a small portion of the variance in cognitive test scores.

DISCUSSION: Only three out of seven cognitive test scores demonstrated differences between exercise groups. Even among those tests that showed differences, higher levels of exercise were not consistently associated with better performance. In some cases, a moderate level of exercise seemed to have an optimal effect with regard to cognitive performance, suggesting the possibility of a dosing effect of exercise. Overall these findings suggest that a possible relationship may exist, but additional research is warranted