First, the normal distribution tests demonstrated that the values of skewness and kurtosis for depression across 2011, 2013, and 2015 ranged from 0.84 to 0.97 and from 0.17 to 0.79, respectively; the values of skewness and kurtosis for CRP across 2011 and 2015 ranged from 1.96 to 2.34 and from 4.29 to 6.25, respectively (detailed information in Supplementary Table S1). Here, CRP is linked to depressive symptom measurement.