Randomized controlled trial on feedback-informed internet-delivered psychodynamic therapy for adolescents with depression: A trial that failed to recruit enough participants.

Background: Internet-delivered psychodynamic therapy (IPDT) has been found to be effective for adolescents with depression in previous randomized controlled trials. The present study aimed to evaluate an adaptive, feedback-informed version of IPDT, designed to improve outcomes for participants identified early as at risk of non-response. Methods: A randomized controlled trial targeting adolescents aged 15-19 years with mild to moderate major depressive disorder. Participants were recruited through social media, national and local advertising, schools, and user organizations. After three weeks of standard IPDT, participants classified as at risk by a prediction algorithm were randomized to either adapted or standard treatment. The planned sample size was 240 participants. Despite extensive nationwide recruitment efforts during 2024, only 35 participants were enrolled before the study was discontinued. Results: Recruitment difficulties were primarily due to recent European Union regulations prohibiting profiling-based online advertising for minors, which eliminated access to previously effective social media recruitment channels. Participants who completed treatment showed significant pre- to post-treatment improvements in depressive symptoms ( Conclusions: Although the trial was underpowered, the findings provide promising within-group effects and valuable lessons for future digital mental health research involving minors. New recruitment infrastructures that comply with data protection laws are needed to ensure feasibility of online psychotherapy trials. Continued development of adaptive, feedback-informed IPDT for adolescents with depression is needed. Trial registration: ClinicalTrials.gov Identifier: NCT06193772.