EXCEED THE SPACE PROVIDED. The proposed studies build upon a program of research conducted under grant AG 12448 to characterize and contrast variability'in intellectual function of young adults, healthy older adults, and older adults at high risk for developing Alzheimer's disease. This research will provide necessary tests of cognitive aging theories and will refine measurement strategies to improve the ability to track changes in cognitive function in aging individuals. These studies will also distinguish the day-to-day variabilityin memory performance that is typical of healthy older adults from the kind of variability associated with an elevated risk of developing dementia. This research is predicated on the view that theories of cognitive aging must be grounded in an accurate and thorough understanding of cognitive function in individuals and must describe thequantitative aspects of age-related change, as well as describe qualitative differences between young and older adults.Most aging research ignores the fact that cognitive function varies considerably within individuals from day to day and instead focuses on apparently stable aspects of cognitive abilities observed at the group level of analyses. Measuring an individual's cognitive performance day after day and studying how performance varies and changes in that individual will provide a more intimate picture of how cognition functions than would measuring many individuals once and analyzing how they differ. Three complementary longitudinalstudies will address four research aims:
Aim 1 : Characterize and model age-effects on short-term intra-individual cognitive variability;
Aim 2 : Optimize measurement and detection of short-term and long-term cognitive change;
Aim 3 : Test common factor cognitive aging theories at the intraindividual level;
Aim 4 : Evaluate the assumption of ergodicity, which postulates that patterns of age effects on means, variances, and covariances observed at the population level (between-persons) are equivalentto results observed at the individual level (within-persons). PERFORMANCE SITE ========================================Section End===========================================
