The connecting adolescents to reduce relapse (CARR) trial: study protocol for a randomized controlled trial comparing the efficacy of Groups 4 Health and cognitive behaviour therapy in young people

Background Depression is the leading cause of disability in young people (aged 15–25) globally. Loneliness is a major factor in the development and relapse of depression in young people, yet few interventions directly address loneliness. Groups 4 Health (G4H) – a novel, theoretically derived group psychotherapy intervention – may address this disconnect. Previous trials (Phase I and Phase II) have found G4H to be efficacious in reducing symptoms of depression. However, the efficacy of G4H compared to current evidence-based treatments (Phase III) has not been investigated. This protocol details the design and methodology of the Connecting Adolescents to Reduce Relapse (CARR) trial, a randomised control trial assessing the efficacy of G4H in young people relative to cognitive behavioural therapy (CBT).