The Role of Smoking, Obesity, and Physical Inactivity in Cognitive Performance and Decline: A Multicohort Study.

This article investigates the impact of three lifestyle factors—smoking, obesity, and physical inactivity—on cognitive performance and the rate of cognitive decline across different birth cohorts using longitudinal data from four large-scale cohort studies (China Health and Retirement Longitudinal Study, English Longitudinal Study on Ageing, Health and Retirement Study, and Survey of Health, Ageing and Retirement in Europe) encompassing 14 countries. The study found that individuals who engaged in moderate or vigorous physical activity, were noncurrent smokers, and maintained a weight above underweight status exhibited higher cognitive function scores in episodic memory, working memory, and time orientation, as well as slower rates of cognitive decline. Notably, being underweight was associated with worse cognitive outcomes, while overweight and obesity showed some protective associations with cognitive function. These findings underscore the importance of promoting healthy lifestyle behaviors—such as tobacco control, physical activity, and preventing underweight—to mitigate cognitive decline and support healthy aging globally.