A Scalable Trans Diagnostic Intervention Targeting Adolescent Agency Supported by Conversational AI (AGENCIA)

The aim of this clinical trial is to evaluate whether AGENCIA, a brief psychological program supported by digital technology and artificial intelligence, can help reduce emotional and behavioral difficulties in adolescents aged 12 to 18. These difficulties may include irritability, impulsive behaviors, conflicts at home or at school, or difficulties in managing intense emotions. The study also aims to determine whether the effects are similar across adolescents with different symptom profiles or neurodevelopmental characteristics. Participants will be randomly assigned to one of three groups: AGENCIA Digital: a self-guided online version completed at home. AGENCIA in-person with a digital assistant: a clinician-delivered version supported by an interactive digital assistant to guide the exercises. Digital psychoeducation (control): a self-guided online program providing general information about adolescent well-being. The main research questions are: Does AGENCIA reduce overall emotional and behavioral difficulties? Does the program improve functioning, family accommodation, and personal agency (a young person's sense of being able to act and make changes)? Are the effects similar across adolescents with different profiles or neurodevelopmental characteristics? Participants will: * Complete three structured sessions depending on their assigned group. * Complete brief online questionnaires at baseline (T0), immediately after the sessions (T1), and at 1-month (T2) and 6-month (T3) follow-ups. * Receive brief phone calls during follow-ups to support questionnaire completion. A total of 465 adolescents will take part in the study. Participation is voluntary and does not replace usual clinical care. The study does not involve medication or invasive procedures, and all digital tools operate within secure institutional systems.