The Impact of Age on Cognition.

This article reviews the cognitive changes that occur with normal aging, the structural and functional correlates of these cognitive changes, and the prevalence and cognitive effects of age-associated diseases. Understanding these age-related changes in cognition is important given our growing elderly population and the importance of cognition in maintaining functional independence and effective communication with others. The most important changes in cognition with normal aging are declines in performance on cognitive tasks that require one to quickly process or transform information to make a decision, including measures of speed of processing, working memory, and executive cognitive function. Cumulative knowledge and experiential skills are well maintained into advanced age. Structural and function changes in the brain correlate with these age-related cognitive changes, including alterations in neuronal structure without neuronal death, loss of synapses, and dysfunction of neuronal networks. Age-related diseases accelerate the rate of neuronal dysfunction, neuronal loss, and cognitive decline, with many persons developing cognitive impairments severe enough to impair their everyday functional abilities. There is emerging evidence that healthy lifestyles may decrease the rate of cognitive decline seen with aging and help delay the onset of cognitive symptoms in the setting of age-associated diseases.