The cognitive reserve hypothesis: a longitudinal examination of age-associated declines in reasoning and processing speed.

The term cognitive reserve is frequently used to refer to the ubiquitous finding that, during later life, those higher in experiential resources (e.g., education, knowledge) exhibit higher levels of cognitive function. This observation may be the result of either experiential resources playing protective roles with respect to the cognitive declines associated with aging or the persistence of differences in functioning that have existed since earlier adulthood. These possibilities were examined by applying accelerated longitudinal structural equation (growth curve) models to 5-year reasoning and speed data from the no-contact control group (N = 690; age 65-89 years at baseline) of the Advanced Cognitive Training for Independent and Vital Elderly study. Vocabulary knowledge and years of education, as markers of cognitive reserve, were related to levels of cognitive functioning but unrelated to rates of cognitive change, both before and after the (negative) relations between levels and rates were controlled for. These results suggest that cognitive reserve reflects the persistence of earlier differences in cognitive functioning rather than differential rates of age-associated cognitive declines.