Bi-directional associations between depressive symptoms and asthma in middle-aged and elderly adults in China

There is currently no evidence of an association between depressive symptoms and asthma among older adults in China. We explored the bi-directional associations between depressive symptoms and asthma, and their changes in middle-aged and elderly adults from a national cohort. A longitudinal cohort study was conducted with a total of 17,708 individuals from 150 urban communities and 450 rural villages in 28 provinces in China. After making exclusions, 11,492 and 8604 participants were included for incident asthma and incident depressive symptoms analysis, respectively. The incidence density was 4.46 and 10.24 for every 1000 person-years, respectively. Baseline depressive symptoms were associated with a higher risk of incident asthma (Hazard ratio [HR] = 1.60, 95 % confidence interval [CI]: 1.27, 2.02). Decreased depressive symptoms during baseline or follow-ups or both baseline and follow-ups were associated with a lower risk of incident asthma (Pfor trend < 0.0001). Every 1-score increment of CES-D score was associated with a 4 % increase in asthma, with a non-linear association (P = 0.04) between CES-D score (break point = 7) and asthma. Asthma status increased the risk of participants with severe depressive symptoms (HR = 1.51, 95 % CI: 1.19, 1.92), especially in males (Pfor interaction = 0.02). Depressive symptoms and asthma were assessed by validated questionnaires instead of clinical diagnosis. Bi-directional associations between asthma and depressive symptoms do exist. Effective measures should be taken to reduce depressive symptoms and the risk of incident asthma in middle aged and elderly adults in China.