Engagement in cognitively stimulating activities has been considered to maintain or strengthen cognitive skills, thereby minimizing age-related cognitive decline. While the idea that there may be a modifiable behavior that could lower risk for cognitive decline is appealing and potentially empowering for older adults, research findings have not consistently supported the beneficial effects of engaging in cognitively stimulating tasks. Using observational studies of naturalistic cognitive activities, we report a series of mixed effects models that include baseline and change in cognitive activity predicting cognitive outcomes over up to 21 years in four longitudinal studies of aging. Consistent evidence was found for cross-sectional relationships between level of cognitive activity and cognitive test performance. Baseline activity at an earlier age did not, however, predict rate of decline later in life, thus not supporting the concept that engaging in cognitive activity at an earlier point in time increases one's ability to mitigate future age-related cognitive decline. In contrast, change in activity was associated with relative change in cognitive performance. Results therefore suggest that change in cognitive activity from one's previous level has at least a transitory association with cognitive performance measured at the same point in time.

We initiated this project with a set of concerns about the future of cognitive aging research and a determination to raise a number of critical questions about the direction the field of cognitive aging is going. We asked a wide range of questions that we and others believe the field should be asking—including questions about the theoretical perspectives that should be brought to bear on understanding processes of cognitive aging, the current state of our knowledge across the broad spectrum of human abilities and functional capacities, and the kinds of research strategies and measurement approaches that will be needed in future work.

Researchers who study human development are interested in how psychological, physiological, and behavioral phenomena change over time in aging individuals. In fact, Baltes and Nesselroade (1979) identified the primary objective of longitudinal developmental research as the “direct identification of intraindividual change” (p. 23). However, this goal is complicated by the possibility that observable change in any given individual may reflect the joint influences of multiple processes. For example, observable decreases in memory performance over time (i.e., with increasing age) may reflect the complementary effects of declining vascular health and the progression of Alzheimer’s dementia (Sliwinski, Hofer, Hall, Buschke, & Lipton, 2003; Sliwinski, Lipton, Buschke, & Stewart, 1996). In contrast, observable change in cognitive performance may reflect a mixture of competing influences, such as aging-related declines that are partially or completely offset by performance gains attributable to repeated testing (i.e., retest or practice effects). The purpose of this chapter is to examine a novel approach to decompose age (decline) and retest (gains) effects in longitudinal data. Specifically, we argue that conventional longitudinal designs consisting of repeated and widely spaced single measurements are significantly limited in their ability to disentangle multiple time-dependent processes, such as practice gains and age-related declines in cognition. We present an alternative approach that relies on the longitudinal measurement burst design (Nesselroade, 1991) and a nonlinear measurement model that represents cognitive performance as a function of previous experience and latent potential (i.e., asymptotic performance).

The objectives of this symposium were to evaluate aging-related cognitive change in the context of change in health, and to compare and synthesize patterns of results across multiple longitudinal studies of aging.