Background
Depression is a prevalent mental health condition with a significant global burden, yet treatment coverage remains limited. Digital interventions offer a promising avenue for expanding access to evidence-based interventions.

Methods
In a three-arm randomized clinical trial, we evaluated the efficacy and safety of an app-based intervention and an online group cognitive behavioral therapy (GCBT) to reduce depressive symptoms compared to a waiting list control (WLC). Participants (N=109) with PHQ-9 scores ≥9 were randomized into three groups. Informed consent was obtained. The primary outcome, depressive symptoms, was assessed at baseline and every 4 weeks over 12 weeks. Secondary outcomes included anxiety symptoms, loneliness perception, and treatment-related adverse effects. We used one-tailed Student’s t-tests and Mann-Whitney U tests, adjusting p-values for false discovery rate. Statistical significance was set at 5%. ClinicalTrials.gov identifier: NCT05450614.

Results
After excluding dropouts, 58 participants remained (28 app; 19 GCBT; 11 WLC). Most were women (app: 86%; GCBT: 89%; WLC: 100%) and identified as white (app: 61%; GCBT: 63%; WLC: 82%), aged 36 to 39, with high income and education. Only GCBT showed a significant reduction in anxiety (t(23.92) = 2.20, p = 0.019; padj = 0.038; Cohen’s d = 0.81, 95% CI [0.17, ∞). The remaining comparisons were not statistically significant.

Conclusion
While only GCBT showed significant improvement in anxiety symptoms, both treatments showed trends toward depressive symptom reduction. High dropout rates and a small sample may have impacted results. Further research should assess the long-term impact and scalability of digital interventions in mental health.