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

Abstract

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.

Figures

Figure 1

Distribution of education by age group.

Figure 2

Left: Plot of Age × Vocabulary interaction predicting cross-sectional reasoning performance. Right: Plot of Age × Vocabulary interaction predicting cross-sectional speed performance. In both plots high and low vocabulary are at one standard deviation above the mean, and one standard deviation below the mean, respectively.

Figure 3

Path diagram depicting the multiple group accelerated latent growth curve model employed. BL, PT, Y1, Y2, Y3, and Y5 represent vocabulary or speed performance at baseline, 12 week post test, first annual, second annual, third annual, and fifth annual assessments respectively. Beneath these labels are the designated ages of each age group at each occasion. See text for further description.

Figure 4

Model implied population components of 5 year longitudinal change in reasoning performance.

Figure 5

Model implied components of 5 year longitudinal change in speed performance.