Abstract
Previous studies have shown that cognitive performance in midlife has changed across historical time, and the rate and direction of these historical changes considerably vary across nations/regions. We investigate whether historical shifts in midlife episodic memory are mediated by socio-demographic (education and wealth) and health-related factors (health conditions and depressive symptoms) that have changed over historical time and that are closely related to cognitive functioning. We analyzed harmonized data from nationally representative longitudinal panel surveys across a total of 16 nations (USA, Mexico, China, England, and countries in Continental, Mediterranean, and Nordic Europe). Our study sample consisted of middle-aged individuals (45–65 years; year of birth range 1930–1974), who provided 339,697 observations. In multilevel mediation models, both separately by nation and mediator, as well as in conjoint models, the mediating effects of education, wealth, health conditions, and depressive symptoms were statistically significant in most nations/regions, indicating that historical change in midlife episodic memory is partially driven by historical changes in these variables. The nations differed in the magnitude of historical change in episodic memory, the mediators, and the size of the mediating effects. The U.S. was the only nation for which no historical decline in health conditions was observed, and only the U.S. and Mediterranean Europe exhibited historical trends towards lower midlife wealth. Our findings suggest that across high-income and upper-middle-income nations, historical change in midlife episodic memory is partially mediated by historical trends in socio-demographic and health factors.
•The Flynn effect has rarely been investigated with a focus on midlife.•Little is known about mediators (e.g., health) underlying the Flynn effect.•Socioeconomic (e.g. education) and health indicators were identified as mediators.•The role of these mediators varied considerably across countries and regions.