Effects Of Exercise On Neurocognitive Resting State Networks In Early Stage Breast Cancer

PURPOSE: Decline in cognitive function has been associated with early-stage breast cancer. Although exercise improves cognitive function in late life, there have been conflicting reports of exercise to enhance cognitive function in breast cancer. In this study, we examined the effects of aerobic exercise on brain functional connectivity (FC) within resting state networks (RSNs) in postmenopausal women with early-stage breast cancer. METHODS: All participants completed baseline cardiorespiratory fitness (CRF) testing and a resting state functional magnetic resonance imaging (rsfMRI) scan. Participants were randomized to an exercise group that performed 150 minutes of moderate intensity exercise per week for 6 months or to a usual care group. This study examined participants (N = 34, Age = 63.59 ± 5.73 years, 17 in exercise group), who completed baseline and follow-up MRI brain scans. Three core neurocognitive RSNs, default mode (DMN), salience (SN) and central executive (CEN), were extracted by performing independent component analysis (ICA) on rsfMRI data. FC within and between the three RSNs was measured using the CONN toolbox. Multiple regression analyses were performed to examine post-intervention FC changes and the association between FC and CRF. RESULTS: The exercise group had significant decreased post-intervention FC between the medial prefrontal cortex (mPFC) and the left angular gyrus (lAG) as well as between the lAG and the right inferior parietal lobule (rIPL)(P < 0.05), while the usual care group showed no significant differences in FC after 6 months. After controlling for age and education, stronger between network (DMN-SN and DMN-CEN) FC strength was associated with higher CRF levels (P < 0.05) at both baseline and post-intervention for the exercise group. In addition, the percent change in CRF for the exercise group was associated with FC changes between anterior cingulate cortex (ACC) and lAG as well as between rAG and rIPL. CONCLUSION: Our preliminary data indicate that a 6-month moderate intensity exercise intervention could alter FC of RSNs in postmenopausal women with breast cancer and that these changes might be related to the magnitude of change in CRF levels. Enhancing fitness and exercise might be an effective intervention for mitigating neurocognitive losses associated with cancer.