Abstract
BACKGROUND: Concerns about the consequences of rapid population aging in the USA and England often neglect the key demographic processes of cohort succession and its influence on population health. In this study, we quantify the extent to which trends between 2004 and 2018 in older US and English adults' cognition functioning are related to population composition changes in three areas: (i) age distribution, (ii) socioeconomic factors, and (iii) chronic disease prevalence. METHODS: Using data from the USA-based Health and Retirement Study (n = 17 305 person-years) and the English Longitudinal Study of Aging (n = 7557 person-years), we apply the Kitagawa-Oaxaca-Blinder two-fold decomposition to estimate the contributions of changes in each country's population composition to changes in overall cognitive functioning between 2004 and 2018. RESULTS: For both men and women, improvements in cognitive functioning were largely driven by cohort succession increasing the average educational attainment of the two populations. Increases in the proportions of the youngest old adults counteracted the negative contributions of increased proportions of the oldest adults. However, increases in the prevalence of psychological conditions (for US men, US women, and English women) and the prevalence of diabetes and divorce (for US women) emerge as specific risk factors that are detrimental to continued gains in cognitive functioning. CONCLUSION: Population aging may not necessarily portend an increasing burden of cognitive diseases when cohorts bring different socioeconomic and health protective and risk factors with them into older adulthood.