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

## TL;DR

A study aimed to improve internet-based therapy for depressed adolescents using feedback and a prediction algorithm but failed to recruit enough participants due to EU advertising restrictions.

## Contribution

Development of a feedback-informed internet-delivered psychodynamic therapy with a predictive algorithm for early identification of non-responders.

## Key findings

- Only 35 participants were recruited instead of the planned 240 due to EU regulations on social media ads for minors.
- Participants who completed treatment showed significant improvements in depressive symptoms, anxiety, and emotion regulation.
- The predictive algorithm showed promise in identifying responders and non-responders to treatment.

## Abstract

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.

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.

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 (d = 1.08), anxiety (d = 0.74), and emotion regulation (d = 0.79). The predictive algorithm showed promising results in classifying patients as responders or non-responders.

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.

ClinicalTrials.gov Identifier: NCT06193772

•This randomized controlled trial was designed to evaluate a feedback-informed version of internet-delivered therapy.•A predictive algorithm had been developed to identify participants at risk of non-response after three weeks of treatment.•The trial met challenges in recruiting participants, due to recent EU regulations against social media ads for minors.•Hence, only 35 participants were included, instead of the planned sample size of 240 participants.

This randomized controlled trial was designed to evaluate a feedback-informed version of internet-delivered therapy.

A predictive algorithm had been developed to identify participants at risk of non-response after three weeks of treatment.

The trial met challenges in recruiting participants, due to recent EU regulations against social media ads for minors.

Hence, only 35 participants were included, instead of the planned sample size of 240 participants.