While animal and human studies indicate cognitive benefits from aerobic exercise across the lifespan, the great majority of controlled exercise studies in humans have been restricted to elderly individuals. Those studies have indicated that enhancing aerobic capacity has a beneficial effect on cognition. One study suggests that this benefit is seen particularly for executive control processes, precisely the processes affected by aging. These improvements have been accompanied by increases in gray matter density and changes in functional magnetic resonance imaging (fMRI) patterns of task-related activation. The goal of the proposed study is to extend the investigation of the beneficial effects of aerobic exercise to younger individuals, and to compare these effects in young and old.~In this application the study team propose to conduct a study in which 270 sedentary but otherwise healthy and cognitively intact individuals in the 20-68 year age range are randomized to two training conditions, aerobic exercise and stretching/toning, to be completed at YMCAs and YMHAs in New York City. Participants will be assessed for aerobic capacity, cognitive task performance, and by structural MRI, resting cerebral blood flow scans (arterial spin labeling) and cognitive activation fMRI studies at study entry and after 6 months of training.~The study also proposes two complementary approaches to investigating the neural correlates of the beneficial effects of aerobic exercise on cognition: 1) imaging -- a combination of structural, metabolic, and cognitive activation fMRI studies to evaluate the neural substrates of the effect of aerobic exercise on cognition will be used. 2) important correlates -- the effects of apolipoprotein E (APOE) genotype, inflammatory markers and cognitive reserve on the cognitive effects of aerobic exercise will be explored.
The purpose of this study is to test the hypothesis that aerobic exercise leads improved cognitive function accompanied by increases in gray matter density and changes in functional magnetic resonance imaging (fMRI) patterns of task-related activation.