Non-Suicidal Self-Injury Digital Psychotherapy Trial

The goal of this randomized, parallel-controlled clinical trial is to investigate multi-dimensional biomarkers (blood, brain imaging, clinical information, and symptom assessment) in adolescents with Non-Suicidal Self-Injury (NSSI) and to evaluate the therapeutic and prognostic effects of a novel digital psychological intervention plus treatment as usual (TAU) compared to TAU alone in this population. The main question\[s\] it aims to answer \[is/are\]: What are the distinct biomarker profiles (e.g., inflammatory, endocrine, neuroimaging) associated with adolescent NSSI? Does the novel digital psychological intervention (based on CBT and DBT) combined with TAU lead to a higher clinical response rate (≥25% reduction in NSSI scale score from baseline) at 8 and 16 weeks compared to TAU alone? If there is a comparison group: Researchers will compare the digital intervention plus TAU group to the TAU-only group to see if adding the digital intervention significantly improves NSSI symptom reduction, depressive symptoms (HAMD-24 response rate), and long-term outcomes. Participants will: Undergo baseline assessments including blood sampling (inflammatory and endocrine markers, routine biochemistry), structural and resting-state functional MRI, and clinical scales (e.g., HAMD, HAMA). Use a smartphone app for 8 weeks, completing 16 self-guided digital modules (2 per week, 15-25 minutes each) based on CBT and DBT, covering topics such as NSSI psychoeducation, safety planning, emotion regulation, distress tolerance, mindfulness, and relapse prevention. Complete daily Ecological Momentary Assessment (EMA) questionnaires (1-2 minutes) on self-harm urge intensity, mood, and coping skills used; receive Ecological Momentary Intervention (EMI) when high urge is detected. Receive low-intensity remote coaching (one 20-30 min onboarding call, then two brief contacts per week via text/call/email) to support app adherence. Attend follow-up assessments at week 4, week 8 (intervent