Effects of Aerobic Training on Cognition and Brain Glucose Metabolism in Subjects with Mild Cognitive Impairment

Background: Aerobic training (AT) is a promising intervention for mild cognitive impairment (MCI). Objective: To evaluate the effects of AT on cognition and regional brain glucose metabolism (rBGM) in MCI patients. Methods: Subjects performed a twice-a-week, moderate intensity, AT program for 24 weeks. Assessment with ADAS-cog, a comprehensive neuropsychological battery, and evaluation of rBGM with positron emission tomography with 18F-fluorodeoxyglucose ([18F]FDG-PET) were performed before and after the intervention. Aerobic capacity was compared using the maximal oxygen consumption VO2max (mL/Kg/min). [18F]FDG-PET data were analyzed on a voxel-by-voxel basis with SPM8 software. Results: Forty subjects were included, with a mean (M) age of 70.3 (5.4) years and an initial Mini-Mental State Exam score of 27.4 (1.7). Comparisons using paired t-tests revealed improvements in the ADAS-cog (M difference: −2.7 (3.7), p < 0.001) and VO2max scores (M difference: 1.8 (2.0) mL/kg/min, p < 0.001). Brain metabolic analysis revealed a bilateral decrease in the rBGM of the dorsal anterior cingulate cortex, pFWE = 0.04. This rBGM decrease was negatively correlated with improvement in a visuospatial function/attentional test (rho =−0.31, p = 0.04). Several other brain areas also showed increases or decreases in rBGM. Of note, there was an increase in the retrosplenial cortex, an important node of the default mode network, that was negatively correlated with the metabolic decrease in the dorsal anterior cingulate cortex (r =−0.51, p = 0.001). Conclusion: AT improved cognition and changed rBGM in areas related to cognition in subjects with MCI.