The influence of fitness on age-related changes in cortical activation associated with cognitive function
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Brain function generally declines with age after the fifth decade. EEG Studies generally report that low- frequency EEG activity decreases with age while high-frequency EEG increases, the latter possibly for compensatory reasons. Because exercise has been reported to improve brain neurobiology such as cerebral metabolism and neurotransmitter function, it was expected that exercise would attenuate the age-related changes in EEG activity. Participants were men and women aged 18-35 and 60-75 years that were screened on health and indexed on the basis of physical fitness. Continuous EEG was recorded during each of four cognitive task conditions (eyes-closed, eyes-open, analytical, and spatial) using standardized electrode placements (Fz, Pz, Cz, O1, O2, C3, C4, T3, and T4) and referenced to the average of two ear electrodes (A1 and A2). To examine the relationship of physical fitness, age, and task to spectral power, multivariate analyses of variance were employed (2 x 3 x 2 x 9; Age x Fitness x Task x Site). It was predicted that both young and old participants would have a positive relationship between fitness and low-frequency power. However, the elderly group alone was expected to have a negative relationship between fitness and high-frequency power. Results of the study indicated that aging was associated with substantial changes in cortical dynamics. Furthermore, although the elderly brain appeared to be working in a more effortful manner, fitness did not seem to substantially alter cortical dynamics in relation to fitness level.