The objectives of the proposed research are to determine whether findings of cross-sectional age differences correspond to longitudinal changes in memory in older adults and to evaluate hypotheses regarding memory deficits in older adults. There is a large literature on age differences in memory demonstrating that older adults have deficits in episodic memory, and considerable effort is devoted to identifying the mechanisms of those deficits. Yet few studies have documented how memory changes in individuals as they age. The significance of the present research program is that it charts longitudinal change in memory, it assesses individual differences in memory change and the sources of those differences, it uses multiple changes of all cognitive constructs and structural equation models to analyze the data, and it includes experiments to test new models of cognitive change, which may then be incorporated into the study for future evaluation of longitudinal slopes. The study uses multi-sample sequential designs that collect data from adults in ranging in age from 30-97 and follows them longitudinally at 3-year intervals. Longitudinal changes are compared with changes estimates from cross-sectional samples collected as part of the project to evaluate the effects of age changes and cohort differences. This makes it possible to evaluate the external validity of cross sectional designs, which re the rule in memory. The role of individual differences in longitudinal memory performance is investigated through analyses of changes in memory predictors including psychometric abilities related to fluid and crystallized intelligence, working memory perceptual speed, and retrieval, as well as demographic characteristics including gender, education, health, and affective status. These data will test the hypothesis that predictors of memory change vary with the requirements of the memory tasks using latent change modeling. For example, it is expected that cognitive slowing and retrieval will best predict problems in retrieving unrelated words from a list, whereas working memory deficits will best predict problems in discourse memory. The results of this research will not only provide answers to important methodological questions regarding the parameters of age changes in memory, but also address a number of issues related to individual differences in intra-individual change with age in cognition, and suggest possible mechanisms of age change in memory in healthy older adults.
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