Switching Medication and Augmentation Strategies for SSRI-Resistant Adolescent Depression（SMART-I)

Inclusion Criteria: 1. Aged 12-17; 2. As assessed by K-SADS-PL, it meets the DSM-5 criteria for MDD; 3. CDRS-R≥45; 4. CGI-S≥4; 5. Failed to respond to an initial SSRI trial: the trial at least 8 weeks, with the last of which were at a dosage of at least 40 mg per day of fluoxetine or its equivalent. Exclusion Criteria: 1. Current or lifetime diagnosis of bipolar disorder, schizophrenia, autism, attention-deficit/hyperactivity disorder or obsessive-compulsive disorder or psychosis not otherwise specified; 2. MDD with psychotic symptoms; 3. YMRS\>13; 4. Current or lifetime diagnosis of serious neurologic diseases such as epilepsy, brain trauma or other serious physical illnesses; 5. Failure to respond adequately to two or more antidepressant treatment trials of recommended dose and length (at least 8 weeks, with the last 4 of which were at a dosage of at least 40 mg per day of fluoxetine or its equivalent); 6. History of clear-cut intolerability of, or lack of effect with, an adequate trial of sertraline, agomelatine, or aripiprazole; 7. Current depressive episode with clear suicidal plans or behaviors; 8. Received modified electroconvulsive therapy within 3 months; 9. Taking any medicine that contraindicates in combination with or interferes with the efficacy of the treatment; 10. Substance abuse or dependence; 11. Female patients with pregnancy.