CADS-D aimes to evaluate the effectiveness and feasibility of a newly DCBT program for Chinese adolescents with depressive symptoms.

CADS-D is a single-center, two-arm, open-label randomized controlled trial. The trial targeted 12-18 years adolescents with depressive symptoms. Intervention group receives the digital cognitive behavioral therapy (DCBT) program for 6 weeks, while the control group receives the regular mental health curriculum provided by school staff for 6 weeks. Assessments are conducted at three time points: baseline, post-intervention (6 weeks), and at 3 months follow-up (18 weeks). The primary outcome is the effectiveness of DCBT. Secondary outcomes include the feasibility of DCBT, self-reported depressive severity, anxiety severity, psychological resilience, and the quality of life enjoyment and satisfaction.

Inclusion Criteria:

1. Age 12 to 18 years;
2. Scored 28 or higher on the children's depression rating scale-revised (CDRS-R);
3. Have the ability to read and write in Chinese;
4. Participant and at least one of their guardians provided written consent;
5. Have access to mobile phone and internet.

Exclusion Criteria:

1. The researchers assessed that the adolescent's depressive symptoms were too severe to participate to CADS-D;
2. Scored 5 or higher on item 13 (suicidal ideation) on CDRS-R;
3. Participants who met diagnosis of other mental disorder except depression;
4. Severe physical illnesses or other physical disabilities that prevented the use of DCBT;
5. Within the past three months or currently undergoing any antidepressant treatment, including medication therapy, psychotherapy, and physical therapy;
6. Unavailability to follow up months after intervention.

As the intervention measure set in this study, it is impossible to blind participants or intervention providers. Trained research assistants who are blinded to intervention will conduct the assessment, and data analyst are kept blind to the allocation.