Education and cognitive decline: An integrative analysis of global longitudinal studies of cognitive aging.

BACKGROUND: The objective of this study was to examine the association between education and incidence of accelerated cognitive decline.

METHODS: Secondary analyses of data from the Health and Retirement Study (HRS), a nationally representative prospective cohort study of U.S. residents were conducted (N=28,417). Cox proportional hazards survival models were layered on longitudinal mixed-effects modeling to jointly examine healthy cognitive aging and incidence of accelerated cognitive decline consistent with patterns seen in preclinical Alzheimer's disease and related dementias (ADRD). Replication analyses were completed on a database including 62,485 additional respondents from HRS sister-studies. Life-expectancy ratios (LER) and 95% confidence intervals were reported.

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p>RESULTS: This study replicated research showing that education was positively associated with cognition at baseline. Model fit improved using the survival method compared to random-slopes models alone. Analyses of HRS data revealed that higher education was associated with delayed onset of accelerated cognitive decline (LER=1.031 95% C.I. = [1.013-1.015], P<1E-06). Replication analyses using data from 14 countries identified similar results.

CONCLUSIONS: These results are consistent with cognitive reserve theory, suggesting that education reduces risk of ADRD-pattern cognitive decline. Follow-up work should seek to differentiate specific dementia types involved and consider potential mechanisms.