Educational attainment, time preference, and health-related behaviors: A mediation analysis from the J-SHINE survey.

Evidence consistently shows that low education is associated with unhealthy behaviors. A recent study in behavioral economics argued that high time preferences - the tendency to prefer immediate gain to later reward - explain the limited self-control of individuals in making preventive health-related choices. The aim of this study was to examine the mediating effect of time preference on the associations between education and smoking, binge drinking and overweight in young and middle-aged adults living in a Japanese metropolitan area, using a quantitatively measured time discount rate. A population-based probabilistic sample of residents of 25-50 years of age living in four municipalities within Japanese metropolitan areas where economic disparity is relatively large was obtained from the Japanese Study on Stratification, Health, Income, and Neighborhood (J-SHINE). Respondents answered the questionnaire items using a computer-aided personal instrument (CAPI). Data from 3457 respondents were used in this study. Time preferences measured as categorical responses were converted into a continuous number of time discount rates by using the maximum likelihood method. Smoking habit, binge drinking, and body mass index were regressed on educational attainment with demographics and other confounders. The mediating effects of the time discount rate were examined with the bootstrapping method. Results showed that the time discount rate did not mediate the association between education and binge drinking and BMI. Even for smoking, the mediating effect of time discount rate was quite limited, indicating that the proportion of total effect of education mediated was only 4.3% for men and 3.0% for women. The results suggest that modifying time preferences through educational intervention has only limited efficacy in closing disparities in health-related behaviors, and that other mediators fostered by schooling, such as knowledge/skills, group norms and supportive peers/networks, may be more important as modifiable mediators in the link between education and smoking.