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

Background Unhealthy lifestyles are recognized contributors to cognitive decline, yet limited evidence focuses on their roles in cognitive decline rate. This study examined the role of smoking, obesity, and physical inactivity in cognitive performance and rate of cognitive decline by birth cohort on a global scale.Methods Utilizing data from 4 prospective 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) across 14 countries, a multicohort study was performed. Eligible participants were aged 50 years and older. Linear mixed models were employed to detect the role of smoking, obesity, and physical inactivity in cognitive function domains (epidemic memory, working memory, and time orientation).Results Higher scores of cognitive functions were found in participants who engaged in more vigorous physical activity, were noncurrent smokers, and maintained underweight (eg, for episodic memory scores in females at 60 years, vigorous physical activity: 0.47, 95% CI: 0.46, 0.49). In addition, a slower rate of cognitive decline was also found in individuals who engaged in moderate or vigorous physical activity, were noncurrent smokers, and maintained not being underweight (eg, for episodic memory scores changing from 50 to 70 years old in females, vigorous physical activity: from 0.54 (95% CI: 0.51, 0.57) to 0.40 (95% CI: 0.37, 0.44) and in males from 0.33 (95% CI: 0.30, 0.36) to 0.11 (95% CI: 0.08, 0.14).Conclusions We confirmed the beneficial impact of healthy lifestyles in preventing cognitive decline and promoting healthy aging. Urgent measures are needed to identify and encourage healthy lifestyles, such as strengthening tobacco control, developing policy on physical activity promotion, and preventing underweight, to minimize worldwide levels of cognitive decline.