Aging, training, and the brain: a review and future directions

Abstract

As the population ages, the need for effective methods to maintain or even improve older adults' cognitive performance becomes increasingly pressing. Here we provide a brief review of the major intervention approaches that have been the focus of past research with healthy older adults (strategy training, multi-modal interventions, cardiovascular exercise, and process-based training), and new approaches that incorporate neuroimaging. As outcome measures, neuroimaging data on intervention-related changes in volume, structural integrity; and functional activation can provide important insights into the nature and duration of an intervention's effects. Perhaps even more intriguingly, several recent studies have used neuroimaging data as a guide to identify core cognitive processes that can be trained in one task with effective transfer to other tasks that share the same underlying processes. Although many open questions remain, this research has greatly increased our understanding of how to promote successful aging of cognition and the brain.

Figure 1. Hypothetical functions relating activation of additional regions (e.g., right prefrontal cortex during a verbal working memory task) to load

This figure shows the simplest case, in which activation/load slopes, maximal activation levels, and training benefits are assumed to be equivalent for both age groups. The horizontal line indicates the statistical threshold at which activation is detected. Both age groups show the same basic function in which increasing load is associated with increasing recruitment up to a critical point, after which it declines. (See text.) Older adults reach significant activation levels and the deflection point at smaller load levels than do young adults. Training shifts functions along the load axis for both age groups.

Figure 2. Interventions may have practical benefits even if they do not change the rate of decline

The solid line is an idealized function of general cognitive decline over age; the dashed line indicates the same but with a cognitive intervention (cognitive or cardiovascular training) and booster session. The horizontal dotted line indicates the threshold for clinical or functional impairment (e.g., giving up driving or control of finances, moving from independent to assisted living). Even if the rate of decline returns to normal after temporary shifts in the level of function due to the intervention and booster session, it may delay the point at which an individual reaches sufficient degrees of impairment to impact daily life.