Abstract
Objectives To determine whether the effect of educational attainment on health outcomes is due in part to an effect on smoking behaviour, and whether this is due to educational attainment or general cognitive ability.
Design Multivariable Mendelian randomization using genetic variants associated with educational attainment and general cognitive ability.
Setting Individuals (N = 84,907) in the UK Biobank study.
Main outcome measures Smoking status, including current smoking, ever smoking and smoking cessation.
Results One additional year of education leads to a 4.4% decrease in the probability of being a current smoker (95% CI 6.8% decrease to 1.9% decrease), but there is no clear evidence of an effect of general cognitive ability (coefficient 5.5% increase, 95% CI -0.4% decrease to 11.3% increase). Similar results were obtained for smoking initiation and cessation.
Conclusions More years of education lead to a reduced likelihood of smoking and, among those who do smoke, a greater likelihood of cessation. Given the considerable physical harms associated with smoking, this is likely to account for a substantial proportion of health inequalities associated with differences in educational attainment.