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Yang, Yang Claire; Walsh, Christine E.; Shartle, Kaitlin; Stebbins, Rebecca C.; Aiello, Allison E.; Belsky, Daniel W.; Harris, Kathleen Mullan; Chanti-Ketterl, Marianne; & Plassman, Brenda L. (Online ahead of print). An Early and Unequal Decline: Life Course Trajectories of Cognitive Aging in the United States. Journal of Aging and Health. PMCID: PMC10728348


Objectives: Cognitive aging is a lifelong process with implications for Alzheimer’s disease and dementia. This study aims to fill major gaps in research on the natural history of and social disparities in aging-related cognitive decline over the life span.
Methods: We conducted integrative data analysis of four large U.S. population-based longitudinal studies of individuals aged 12 to 105 followed over two decades and modeled age trajectories of cognitive function in multiple domains.
Results: We found evidence for the onset of cognitive decline in the 4th decade of life, varying gender differences with age, and persistent disadvantage among non-Hispanic Blacks, Hispanics, and those without college education. We further found improvement in cognitive function across 20th century birth cohorts but widening social inequalities in more recent cohorts.
Discussion: These findings advance an understanding of early life origins of dementia risk and invite future research on strategies for promoting cognitive health for all Americans.


Reference Type

Journal Article

Year Published

Online ahead of print

Journal Title

Journal of Aging and Health


Yang, Yang Claire
Walsh, Christine E.
Shartle, Kaitlin
Stebbins, Rebecca C.
Aiello, Allison E.
Belsky, Daniel W.
Harris, Kathleen Mullan
Chanti-Ketterl, Marianne
Plassman, Brenda L.

Article Type




Data Set/Study

National Longitudinal Study of Adolescent to Adult Health (Add Health)
National Survey of Midlife Development in the United States (MIDUS)
Health and Retirement Study (HRS)
Americans’ Changing Lives (ACL) Study


United States




Yang - 0000-0001-7279-1479
Walsh, C - 0000-0002-6190-9491
Aiello - 0000-0001-7029-2537
Harris, KM - 0000-0001-9757-1026