Education and Cognitive Functioning Across the Life Span

Abstract

Cognitive abilities are important predictors of educational and occupational performance, socioeconomic attainment, health, and longevity. Declines in cognitive abilities are linked to impairments in older adults' everyday functions, but people differ from one another in their rates of cognitive decline over the course of adulthood and old age. Hence, identifying factors that protect against compromised late-life cognition is of great societal interest. The number of years of formal education completed by individuals is positively correlated with their cognitive function throughout adulthood and predicts lower risk of dementia late in life. These observations have led to the propositions that prolonging education might (a) affect cognitive ability and (b) attenuate aging-associated declines in cognition. We evaluate these propositions by reviewing the literature on educational attainment and cognitive aging, including recent analyses of data harmonized across multiple longitudinal cohort studies and related meta-analyses. In line with the first proposition, the evidence indicates that educational attainment has positive effects on cognitive function. We also find evidence that cognitive abilities are associated with selection into longer durations of education and that there are common factors (e.g., parental socioeconomic resources) that affect both educational attainment and cognitive development. There is likely reciprocal interplay among these factors, and among cognitive abilities, during development. Education-cognitive ability associations are apparent across the entire adult life span and across the full range of education levels, including (to some degree) tertiary education. However, contrary to the second proposition, we find that associations between education and aging-associated cognitive declines are negligible and that a threshold model of dementia can account for the association between educational attainment and late-life dementia risk. We conclude that educational attainment exerts its influences on late-life cognitive function primarily by contributing to individual differences in cognitive skills that emerge in early adulthood but persist into older age. We also note that the widespread absence of educational influences on rates of cognitive decline puts constraints on theoretical notions of cognitive aging, such as the concepts of cognitive reserve and brain maintenance. Improving the conditions that shape development during the first decades of life carries great potential for improving cognitive ability in early adulthood and for reducing public-health burdens related to cognitive aging and dementia.

Keywords: cognitive ability; cognitive aging; dementia; educational attainment; life-span development.

Fig. 1.

Average number of years of total schooling for individuals ages 25 years or older as a function of time (year), presented separately by country. From “Global Education,” by M. Roser and E. Ortiz-Ospina, 2020 (https://ourworldindata.org/global-rise-of-education), published under a CC BY 4.0 license.

Fig. 2.

Schematic depiction of the importance of both levels of and changes in cognitive performance for understanding functional independence and dementia in older age. People reach functional-impairment thresholds at different points in older age because they start out with different levels of cognitive performance (compare the solid lines), because they experience different rates of cognitive change (i.e., different within-persons development; compare the solid lines with the dashed lines), or because of a combination of those differences. Initial differences between people in levels of performance can affect the age at which cognitive declines significantly interfere with daily life and, in turn, the point at which dementia is diagnosed (compare the two dashed lines). Gf = fluid abilities.

Fig. 3.

Funnel plot and forest plot of effect sizes (observed outcomes) from studies examining the association between education and age-related change in episodic memory. The funnel plot (a) shows standard errors as a function of effect size. Each plotted point represents a single study. The white triangle represents the region where 95% of the data points would lie in the absence of a publication bias, and the vertical line represents the mean effect size. The forest plot (b) shows correlations, represented by squares, reported for individual samples. The area of each square is proportional to the sample’s weight in the meta-analysis, and the horizontal lines represent confidence intervals (CIs). (The correlations and CIs are also provided in the right-hand column.) The red diamond shows the overall measure of the effect from a random-effects (RE) model. Results are shown with outliers removed; with outliers included, the average effect size was similar (−0.0003, 95% CI = [−0.004, 0.004]) to the one shown here (0.0005, 95% CI = [−0.001, 0.002]). Note that positive correlations between educational attainment and cognitive change indicate that greater educational attainment is associated with slower cognitive decline. A negative association indicates that greater education attainment is associated with faster cognitive decline (see Box 1). Adapted from “Education and Age-Related Decline in Cognitive Performance: Systematic Review and Meta-Analysis of Longitudinal Cohort Studies,” by D. Seblova, R. Berggren, and M. Lövdén, 2020, Ageing Research Reviews, Vol. 58. doi:10.1016/j.arr.2019.101005.

Fig. 4.

Schematics illustrating the relation between education and age-based cognitive decline. The graph in (a) summarizes evidence from observational studies indicating that individuals with higher and lower levels of education tend to differ in cognitive ability in early adulthood and, on average, show only small differences in rates of cognitive decline over time. As a result, more highly educated individuals pass a threshold for functional impairments and dementia diagnoses at a later age. Note that if the sample for a study is selected on the basis of a threshold of low performance at a particular age (e.g., 80 years old), then highly educated individuals experiencing a nonrepresentative sharp decline in performance will be overrepresented. The graph in (b) is a more extreme schematic, for illustrative purposes, of the association between education and cognitive performance in adulthood. Note that highly educated and less educated people (with corresponding performance) differ in their rate of cognitive change as they approach the threshold for a dementia diagnosis (more highly educated individuals show faster declines at a later age), although they show parallel cognitive trajectories. This is also the case for individuals with more marked (and pathological) decline than in the general population—for example, individuals who will be diagnosed with Alzheimer’s disease (compare the dashed lines in b). The origin of this effect is the acceleration of decline. Gf = fluid abilities.

Fig. 5.

Results from a meta-analysis of the effects of 1 additional year of education on cognitive performance (IQ points), as a function of the age at which cognitive performance was measured. Effect sizes are from studies that used policy changes (e.g., increases in compulsory schooling that were implemented quasirandomly) to examine the effects of education on performance. Bubble size is proportional to the inverse variance for each estimate (larger bubbles = more precise studies). The shaded area around the regression line represents the 95% confidence interval. From “How Much Does Education Improve Intelligence? A Meta-analysis,” by S. J. Ritchie and E. M. Tucker-Drob, 2018, Psychological Science, 29, p. 1363.