Inclusion Criteria:  aged 18-60 years; diagnosed with moderate or severe depressive disorder according to the criteria of the DSM-5; total score of 17-HDRS≥17; never receiving electroconvulsive therapy (ECT)/modified ECT (MECT)/rTMS or other treatments in the past month; having sufficient audio-visual ability and comprehension; signed informed consent statements.  Exclusion Criteria:  serious or active somatic illness (abnormal index values were more than twice the limit of normal); a history of mania/hypomania; current high risk of suicide (score of item 3 of 17-HDRS ≥ 3); pregnant or lactating women, or planning pregnant women; taking immunosuppressants or vitamins recently.