In addition to the robust literature on the effects of long-term exercise on brain function, a growing literature has also examined the influence of a single bout of exercise, termed вЂњacute exerciseвЂќ, on human behavior. Indeed, studies in both rodents and humans have shown that long-term exercise is helpful in both delaying the onset of cognitive decline and dementia as well as improving symptoms in patients with an already existing diagnosis. Because of the role of exercise in enhancing neurogenesis and brain plasticity, physical activity may serve as a potential therapeutic tool to prevent, delay, or treat cognitive decline. In some instances, neurodegeneration results in mild cognitive impairment or more severe forms of dementia including AlzheimerвЂ™s, ParkinsonвЂ™s, or HuntingtonвЂ™s disease. As we age, cognitive decline, though not inevitable, is a common occurrence resulting from the process of neurodegeneration. As well as for improving cognition in children and healthy adults, these long-term effects of exercise are of particular interest for their possible role in improving cognitive function during aging. The most commonly reported area to undergo improvement is the prefrontal cortex, with exercise-induced enhancements observed in attention and other executive functions. In humans, both behavioral and functional imaging approaches have started to identify the neuroanatomical systems modulated by long-term increases in exercise. Studies in rodents have also documented the neuroanatomical, neurochemical, and cellular/molecular changes associated with long-term exposure to exercise. Animal models have focused mainly on the effects of long-term exercise (i.e., weeks to months of increased exercise) on hippocampal function, with special emphasis on exercise-induced adult hippocampal neurogenesis and hippocampal-dependent learning and memory. In particular, abundant data suggest that physical activity can reduce the risk of various neurological diseases and protect the brain from the detrimental effects of aging. The positive influence of exercise on mood and cognition across the lifespan has become a topic of much excitement.

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