COHORT SHIFTS IN POPULATION COGNITIVE AGING

Abstract

Abstract Declines in cognitive functioning with increased age, on average and individually, is well documented and demonstrated to be related to genetics and a variety of life course risk factors, many of which are modifiable. Related to population cognitive aging is the phenomenon of the Flynn effect, the finding of increasing cognitive test scores across successive cohorts of young adults (e.g., Flynn 1987). This cohort effect has been repeatedly observed, in a wide variety of contexts, for over 30 years, with evidence that it has been occurring for at least a century. Our research looks at the interaction of the population cognitive aging and the Flynn effect. Using data from the English Longitudinal Survey of Ageing (ELSA) we show that, indeed, later born cohorts show significant (and meaningful) differences from earlier born cohorts. Using nonlinear Bayesian modeling we find that, on certain measures, later born cohorts have higher initial ability. This higher ability leads to a persistent advantage for later born cohorts, even as they experience (or will experience) cognitive decline. Additionally, we find that the advantage for later born cohorts is not present for every measure. Later born cohorts show an advantage for verbal fluency and episodic memory, however there is no cohort advantage on orientation scores. The lack of measurable differences on orientation is likely due to ceiling effects on orientation, which suggests that any substantial decline on that measure is indicative of pathology. We discuss the potential factors underlying both population cognitive aging and recent birth cohort trends.