Changes in the Process of Aging During the Twentieth Century: Findings and Procedures of the Early Indicators Project

The program project Early Indicators of Later Work Levels, Disease and Death investigates how socioeconomic and environmental factors in early life can shape health and work levels in later life. Project researchers have approached this problem by creating a life-cycle sample that permits a longitudinal study of the aging of Union Army veterans, the first cohort to reach age 65 during the twentieth century. Comparing Union Army data with data from NHANES and NHIS has shown that age-specific prevalence rates of specific chronic diseases and disabilities were much higher in the century before World War II among both young and old than today. Moreover, the number of comorbidities at each age has fallen sharply. Also, the average age at onset of chronic diseases was more than a decade later at the end of the twentieth century than at the beginning. The implications of these findings for several issues in health economics are discussed.