Physical activity may improve cognitive function in women with breast cancer. In a cross-sectional study, we explored the relationship between cognitive function and physical activity (actigraph) and cardiorespiratory fitness (sub-maximal graded exercise test) in 73 postmenopausal women with early stage breast cancer prior to the initiation of systemic adjuvant therapy. Cognitive function was assessed with a standardized battery of neurocognitive measures assessing eight domains. Data were analyzed using partial correlations, controlling for age and total hours of actigraph wear-time. Women were, on average, 63.71 (± 5.3) years of age with 15.47 (± 2.48) years of education. For physical activity, greater average number of steps per day were associated with better attention (r = .262, p = .032) and psychomotor speed (r = .301, p = .011); greater average hours of moderate and moderate/vigorous intensity physical activity were associated with better visual memory (r = .241, p = .049; r = .241, p = .049, respectively); and greater average daily energy expenditure was associated with better visual memory (r = .270, p = .027) and psychomotor speed (r = .292, p = .017). For fitness, higher peak maximum VO2 was associated with better concentration (r = .330, p = .006), verbal memory (r = .241, p = .048), and working memory (r = .281, p = .019). These results suggest that higher levels of physical activity and cardiorespiratory fitness are associated with better cognitive function in postmenopausal women with breast cancer. Randomized controlled trials (RCT) to examine whether physical activity improves cognitive function in women with breast cancer are warranted. These RCTs should also determine the mechanisms of the influence of physical activity on cognitive function. CLINICAL TRIALS REGISTRATION NUMBER: NCT02793921; Date: May 20, 2016.
Keywords: Breast cancer; Cardiorespiratory fitness; Cognitive function; Physical activity.