Transdiagnostic digital mental health interventions for adolescents

Most mental disorders emerge during adolescence, where subclinical symptoms already contribute to substantial functional impairments and long-term health risks. Yet, adolescents face barriers that impede access to adequate care. To address the resulting care gap a shift towards prevention is imperative. Digital mental health interventions (DMHIs) provide a scalable and low-threshold option that could advance preventive care. Clinical staging models recognize that emerging psychopathology is characterized by heterogeneous and co-occurring symptoms, supporting the use of transdiagnostic approaches to prevention. However, uptake and engagement remain persistent challenges, and few studies have combined transdiagnostic prevention with adolescent perspectives in DMHI development. Thus, this dissertation examines the challenges and opportunities of co-designed transdiagnostic preventive DMHIs for adolescents. To this aim, three articles are discussed. The first article presents a qualitative study of adolescents’ perspectives on DMHIs, focusing on uptake and engagement and highlighting the value of co-design in early development. The second article reports the study protocol of the EMPATIA randomized controlled trial (RCT), a co-designed, transdiagnostic preventive DMHI targeting subclinical symptoms in adolescents from the general population. The third article presents the efficacy results of this RCT. Based on these studies, a framework of the adolescent help-seeking process is proposed, integrating adolescent and research perspectives across pre help-seeking, help-seeking, and post help-seeking phases. The framework offers guidance for future co-design, evaluation and implementation of preventive DMHIs. Finally, implications for future research are outlined, supporting ongoing efforts to translate prevention research into accessible, scalable and evidence-based preventive mental health care for adolescents.

2026

dissertation

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