Assessment of Depression Severity

A validated Chinese version of the Zung SDS was used to assess the severity of depression (Peng et al., 2013). The SDS has 20 items and the score of each item ranges from one to four, with a sum score ranging from 20 to 80. A higher SDS score indicates a greater depression severity. In the current study, SDS scores of ≥40 and ≥45 indicated mild and moderate-to-severe depression, respectively. Accordingly, participants were divided into three groups: normal, mild depression, and moderate-to-severe depression.

Additionally, the SDS also assesses anxiety symptoms via the following five questions: “Do you feel down-hearted and blue?” (Chan et al., 2010), “Do you have trouble sleeping at night?” (Zung, 1971), “Does your heart beat faster than usual?” (Zung, 1971), “Do you get tired for no reason?” (Zung, 1971), and “Do you still enjoy the things you used to?” (Chan et al., 2010). The scores of these five items are summed as a total score, which ranges from 5 to 20; higher scores indicate greater anxiety severity. In this study, anxiety was defined as a score ≥6. In this study, Cronbach’s α coefficient for the SDS was 0.738, indicating a good internal consistency.