Can a 6-week group therapy program help reduce self-injury in young people?

INTERVENTION: This study adopts a prospective, randomized controlled trial design in which eligible participants are allocated to either the intervention group or the control group at a 1:1 ratio. The randomization sequence is generated by an independent statistician not involved in participant recruitment or clinical procedures, using a simple randomization method. To ensure allocation concealment, sequentially numbered, opaque, sealed envelopes (SNOSE) are employed. Specifically, the allocation results are placed into opaque black envelopes according to participant serial numbers (001, 002, …, N). Each envelope is sealed with double‐sided tape and stamped with a cross‐over seal across the closure. All envelopes are arranged in numerical order and transferred in a sealed manner to the principal investigator (or research coordinator) for safekeeping. Once a participant meets the inclusion/exclusion criteria and provides written informed consent, a research assistant who is not involved in group assignment sequentially opens the envelopes, records the allocation, and implements the assigned intervention. The allocation outcome is simultaneously documented in the case report form (CRF). Intervention: Participants in the intervention group receive a 6‐week dialectical behavior therapy (DBT) group skills training program consisting of 12 sessions (90 minutes each, twice weekly). The curriculum covers core DBT skill modules, including: introduction to group skills training (biosocial model); chain analysis of non‐suicidal self‐injury (NSSI) behavior; mindfulness skills (wise mind; “what” and “how” skills); emotion regulation (exploring emotions, building mastery and accumulating positive emotions, cope ahead and PLEASE skills, opposite action); distress tolerance (distracting with ACCEPT CONDITION: Non‐Suicidal Self‐Injury (NSSI) comorbid with Major Depressive Disorder (MDD) or Persistent Depressive Disorder (PDD) in adolescents ; Mental and Behavioural Disorders INCLUSION CRITERIA: 1. Meeting DSM‐5 diagnostic criteria for major depressive disorder or persistent depressive disorder, as confirmed by the MINI screening, and concurrently meeting DSM‐5 diagnostic criteria for non‐suicidal self‐injury disorder (NSSI) 2. Aged between 14 and 19 years 3. Having at least a sixth‐grade education level 4. If taking psychiatric medication, the type and dosage had been stable for at least one month 5. Providing written informed consent from both the participant and their legal guardian, as approved by the ethics committee