Physical Activity, Exercise Physiology, Movement
Exercise Training Alters Resting Cerebral Blood Flow: Implications for MCI and Healthy Older Adults
(School of Public Health (UMD) KNES Doctoral Student)
Mild Cognitive Impairment (MCI) afflicts ~8.6 million Americans over age 65 and increases one’s risk for Alzheimer’s disease (AD). Although a cure remains elusive, exercise training improves both brain structure and function in older adults with and without MCI. Altered cerebral blood flow (CBF), including a compensatory hyper-perfusion in MCI, likely precedes and facilitates changes to the brain’s neural infrastructure, making it a candidate biomarker for health and disease. We examined the effects of a 12-week aerobic exercise intervention on regional CBF (rCBF) in healthy older adults (HOA) and those with MCI. We hypothesized that individuals with MCI would experience the greatest rCBF changes over time. Sixteen HOA and 16 individuals with MCI (age 60-88 years) engaged in 12-weeks of moderate intensity exercise training (4-days/week for 30-minutes). Perfusion weighted images were acquired both before and after the intervention using a GE 3T MR system. A repeated measures ANOVA (AFNI 3dLME) was used to test changes over time and group differences. Whole brain family-wise error correction was maintained at p < 0.05 using an individual voxel probability threshold of p < 0.05 and a cluster size threshold ≥ 41 voxels. Twelve weeks of exercise training resulted in significantly altered rCBF over time. Additionally, we found a significant group x time interaction, in which individuals with MCI experienced greater increases in rCBF than their healthy counterparts. Conclusions: Three months of exercise training altered resting rCBF in those with MCI and to a lesser extent in HOA. These results corroborate existing evidence that exercise training may mitigate the overcompensation often observed in MCI and may improve neural efficiency during memory retrieval (Smith et al. 2013). These effects further suggest that exercise training in those with MCI may promote a normalization of rCBF within a vulnerable and perhaps pathologically disrupted neurovascular system.