RESUMEN
BACKGROUND: Although clinical guidelines prioritize the treatment of depression and anxiety in young persons, there is accumulating evidence that the presence of symptoms of borderline personality disorder (BPD) is associated with the limited effectiveness of these standard treatments. These findings stress the need for interventions addressing early-stage BPD in young people with presenting symptoms of anxiety and depressive disorders. The aim of this study is to investigate the (cost-)effectiveness of an early intervention programme for BPD (MBT-early) compared to first-choice psychological treatment for depression and anxiety according to Dutch treatment guidelines (CBT), in adolescents with either depression, anxiety, or both, in combination with early-stage BPD. METHODS: This study is a multi-centre randomized controlled trial. A total of 132 adolescents, presenting with either depression, anxiety, or both and significant BPD features will be randomized to either MBT-early or CBT. The severity of BPD, symptoms of depression and anxiety, personality, social and academic functioning, and quality of life will be assessed at baseline, end of treatment, and at 12-, 18-, and 24-month follow-up, along with medical costs and costs of productivity losses for cost-effectiveness analyses. DISCUSSION: This study will provide an empirical evaluation of the potential surplus value of early intervention in young people for whom treatment oriented at common mental disorders like anxiety and depression may be insufficient given their underlying personality problems. TRIAL REGISTRATION: Netherlands Trial Register, NL9569. Registered on June 15, 2021.