The Effects of Fitness Differences and Fitness Training on Dual-Task Performance and the Brain Processes of Older Adults

135 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009.Age-related declines in brain structure and function have been well documented. For this reason, it is imperative to develop methods to offset the decline and improve cortical and cognitive function. Physical activity has emerged as one way to improve cognitive function and enhance brain activity in older adults. In this study, I examined the influence of both differences in fitness (cross-sectional study) and training induced fitness benefits (randomized 6 month clinical trial) on the brain function and cognitive performance of aging humans on a well-characterized dual-task paradigm. Functional magnetic resonance imaging scans were collected on all older adults in a paradigm in which participants were asked to judge both letters and numbers. Consistent with extant literatures on cardiovascular fitness, cognition, and aging, I found that increased cardiovascular fitness is associated with increased ability to multi-task. Specifically, higher fit (cross-sectional study) and aerobically trained (longitudinal study) older adults were able to alternate attention more rapidly and process the two tasks more efficiently, as indexed by their performance. In contrast, the older lower-fit and non-aerobically trained older adults had substantially more difficulty during the dual task conditions. Additionally, improvements in cognitive processes engendered by enhanced aerobic fitness were supported by changes in underlying neural circuits as inferred from patterns of event-related fMRI activation. The higher-fit and aerobically trained older adults were better able to adapt to the dual task condition by allocating more mental resources (i.e. increasing activation) in the right middle frontal gyrus of the brain. In contrast, the lower-fit and non-aerobically trained older adults did not activate the middle frontal gyrus as much as the higher-fit older adults. These results provide strong evidence that higher-fit and aerobically trained older adults are more effectively able to manage the cognitively challenging dual task condition by recruiting regions essential for successful task completion. Therefore, it is possible that aerobic exercise can help maintain the functional integrity and impact cortical recruitment in aging individuals.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD