Study Protocol: Single-Arm Pilot Feasibility of a Short-Term Family-Based Mentalization Approach for Early Adolescents with Depression

<ns3:p>Background Adolescent depression affects approximately 13% of youth globally, often emerging before age 14 and leading to long-term impairments in social, academic, and emotional functioning. Evidence suggests that mentalization-based treatment (MBT), particularly its adolescent adaptation, may reduce depressive symptoms by strengthening reflective functioning. Methods This single-arm pilot study will evaluate the feasibility and acceptability of a short-term, family-inclusive MBT intervention for 15 adolescents aged 10–14 years with mild-to-moderate depression in Valparaíso, Chile. The intervention consists of 12 weekly sessions delivered in three phases: shared formulation, promotion of individual and family mentalization, and evaluation of therapeutic progress. Feasibility outcomes include recruitment, retention, and adherence rates. Secondary outcomes include changes in depressive and anxiety symptoms, family cohesion, and therapeutic processes. Qualitative interviews with adolescents, caregivers, and therapists will complement quantitative data. Results The study will generate parameters on feasibility, adherence, and acceptability, as well as preliminary estimates of clinical and process outcomes to inform the design of a future randomized controlled trial. Conclusions Findings will guide the cultural adaptation and potential scaling of adolescent and family MBT within the Chilean public health system. This protocol outlines the methodological framework and expected contributions of the study to clinical practice and research on adolescent depression.</ns3:p>