The dilution effects of healthy lifestyles on the risk of depression attributed to life-course disadvantages among Chinese middle-aged and older adults

Background Life-course disadvantages and unhealthy lifestyles are well-known to independently induce depression, but their joint effects on depression and whether adopting healthy lifestyles can dilute the depressive risks attributed to life-course disadvantages remain unknown in China. Methods Data were from the China Health and Retirement Longitudinal Study. Life-course (childhood and adulthood) disadvantages were defined using 60 questions and were classified as mild, moderate, and severe by principal component analysis. Healthy lifestyles, including regular exercise, reasonable sleep, never smoking, and no heavy alcohol consumption, were classified as 0/1, 2, 3, and 4. Depression was assessed using CESD-10 with cutoff ≥10. Logistic regression was used to investigate the association of life-course disadvantages and lifestyles with depression and the dilution effects of healthy lifestyles on the depressive risks attributed to life-course disadvantages. Results Among 5724 participants included, sleep and smoking mediated 5.1% and 1.1% the effect of severe life-course disadvantages on depression while exercise mediated - 0.8%. Multiple (vs. 0/1) healthy lifestyles were associated with decreased depressive risks more significantly as the life-course disadvantages increased, with odds ratios (ORs) and 95% confidence intervals (CIs) of 0.44 (0.25-0.80) and 0.33 (0.21-0.53) for 4 healthy lifestyles in participants with mild and severe life-course disadvantages, respectively. Compared to participants with mild life-course disadvantages and 4 healthy lifestyles, those who with severe life-course disadvantages and less than one lifestyles were more than 10 times as significantly associated with depression. Finally, participants with mild/moderate life-course disadvantages but ≤2 healthy lifestyles (vs. severe but 4 lifestyles) were not associated with decreased depressive risks. Conclusion Adopting multiple healthy lifestyles can well-dilute the depressive risks attributed to life-course disadvantages in middle-aged and older Chinese, which is of great importance for reducing the depressive burden and the construction of healthy aging in China.