Mortality Selection and Cohort Differences in Patterns of Cognitive Aging

Duane Alwin, Pennsylvania State University
Ryan McCammon, University of Michigan
Linda Wray, Pennsylvania State University
Willard Rodgers, University of Michigan

This paper focuses on the problem of unmeasured heterogeneity in cohort-specific aging functions resulting from mortality selection. Using data from the Health and Retirement Study we examine the possibility of cohort effects on estimates of functions that describe normal cognitive aging. An examination of cohort-specific slopes and intercepts in latent growth curve models of aging functions suggests the existence of significant differences, net of schooling, in cohort-specific intercepts in functions describing normal cognitive aging. One explanation for these cohort differences in intercepts is mortality selection, given the heterogeneity among existing cohort survivors in susceptibility to death and disease. We propose that controlling for cohort differences in expected age at death reduces the observed differences in intercepts, and that it may be important to account for heterogeneity in cohort experiences—including residues of historical experiences, but also variables linked to survivorship in both cross-sectional and longitudinal studies of cognitive aging.