Educational inequalities in aging‐related declines in fluid cognition and the onset of cognitive pathology

Abstract

Background Education has been robustly associated with cognitive reserve and dementia, but not with the rate of cognitive aging, resulting in some confusion about the mechanisms of cognitive aging. This study uses longitudinal data to differentiate between trajectories indicative of healthy versus pathologic cognitive aging. Methods Participants included 9401 Health and Retirement Study respondents aged ≥55 years who completed cognitive testing regularly over 17.3 years until most recently in 2012. Individual-specific random change-point modeling was used to identify age of incident pathologic decline; acceleration is interpreted as indicating likely onset of pathologic decline when it is significant and negative. Results These methods detect incident dementia diagnoses with specificity/sensitivity of 89.3%/44.3%, 5.6 years before diagnosis. Each year of education was associated with 0.09 (95% confidence interval [CI], 0.087–0.096; P < .001) standard deviation higher baseline cognition and delayed onset of cognitive pathology (hazard ratio, 0.98; 95% CI, 0.96–0.99; P = .006). Conclusions Longitudinal random change-point modeling was able to reliably identify incident dementia. Accounting for incident cognitive pathology, we find that education predicts cognitive capability and delayed onset pathologic declines.

Education and Cognitive Decline: An Integrative Analysis of Global Longitudinal Studies of Cognitive Aging

“…Results from this study replicated and extended a prior pilot analysis. Specifically, in their prior analyses (Clouston et al, 2015) used pattern-recognition protocols to lay the foundation for this work. Notably, they determined that acceleration of the sort being investigated here was a good "biomarker" for self-reported incident ADRD diagnoses among individuals with at least five waves of completed cognitive assessments.…”

“…Thus, education does not affect normal aging, but instead changes the point at which accelerated declines due to ADRD occur. Crucial to our ability to test this hypothesis, recent analyses have noted that accelerated declines in cognitive function are fairly common and that they are predictive of incident reports of dementia diagnoses (Clouston, Glymour, & Terrera, 2015). Using the US Health and Retirement Study and a series of replication cohorts, this study extended developmental work by Clouston et al (2015) with the objective being to examine whether education might be independently associated with onset of accelerated cognitive decline in a longitudinal layered survival model that examined, in a generalizable way, population predictors of the onset of ADRD-pattern accelerated declines.…”

“…In this study, we were not able to differentiate subtypes of cognitive pathology. Prior work suggests that accelerated decline is common in patients with ADRD (Ichise et al, 2014;Insel et al, 2016), and has also shown that accelerated declines are often followed by incident reports of ADRD diagnosis (Clouston et al, 2015). To account for cerebrovascular disease, self-reported incident stroke was used.…”

Mental retirement and health selection: Analyses from the U.S. Health and Retirement Study

“…Models account for regression to the mean, and endogeneity in the outcome, and are robust to data that are missing because of factors not related to the rapidity of cognitive decline. However, because we assume linear trajectories of decline, results may be biased by acceleration in declines occurring before dementia (Clouston, Glymour, & Muñiz-Terrera, 2015) or near death (Muñiz-Terrera, Minett, Brayne, & Matthews, 2014). Models adjusted for health conditions that may result in cognitive decline, retirement, and death, but chances for unobserved variability remain.…”

Social engagement and cognitive health in a population-based study of older men and women in rural South Africa

“…However, the social drivers of cognitive health in older LMIC populations are not well understood (Lekoubou, Echouffo-Tcheugui, & Kengne, 2014;Olayinka & Mbuyi, 2014). Education is perhaps the strongest known protective factor against aging-related cognitive decline and dementia (Clouston, Glymour, & Terrera, 2015;Nguyen et al, 2016;Vemuri et al, 2014). However, in many LMICs, school access and quality are limited, especially for those who are now middleaged or older (Kenn, 2016;UNESCO, 2018).…”