Aerobic Exercise and Cerebral White Matter Integrity in MCI Patients

Abstract

Cerebral white matter (WM) represents the structural substrate of neuronal communications and is damaged in dementia patients. Aerobic exercise training (AET) may improve cerebral WM integrity in healthy older adults, but its effect in populations at risk for dementia remains unclear. PURPOSE: To determine the effect of AET on cerebral WM integrity in patients with amnesic mild cognitive impairment (MCI) METHODS: We conducted a 1-year, single-blinded, parallel randomized controlled trial of AET and stretching intervention programs in patients with MCI. At baseline and post intervention, diffusion tensor images (DTI) were acquired to estimate fractional anisotropy and mean diffusivity (MD) that are analyzed by tract-based spatial statistics (TBSS) and compared among the major WM fiber tracts. High-resolution T1-weighted images were also acquired to measure the volumes of cerebral WM and WM hypointensities. Maximal oxygen consumption (VO2max) was measured at pre and post intervention. RESULTS: Thirty-six MCI patients completed AET (n=16) or stretching (n=20) program with the baseline and post-intervention MRI scans. After intervention, participants in AET program improved VO2max while those in stretching group showed slight declines (time × treatment: P=0.008). The volumes of WM and WM hypointensities did not show treatment effects over time (time × treatment: P>0.05). However, TBSS analysis demonstrated that improvements of VO2max with AET are correlated with the reductions of MD among the major WM fiber tracts (Figure). CONCLUSIONS: In patients with amnesic MCI, AET did not improve cerebral WM volume and integrity between the intervention and control groups. However, individual improvements of VO2max were associated with the reductions of MD. These findings suggest that benefits of AET on cerebral WM integrity depend on the magnitude of cardiorespiratory fitness gains. This study was supported by the NIH (R01AG033106 and K99HL133449).Figure