Dysthymia

The goal of this clinical trial is to test the efficacy of a transdiagnostic Internet-delivered interventions for Romanian adolescents with anxiety and/ or depression. The main questions it aims to answer are: * What is the clinical efficacy of the Internet-delivered intervention? * How accurate is the prediction model in predicting who will respond to treatment? Participants will undergo non-invasive fMRI to measure variability in brain signal as a proxy of the neural systems' adaptability before receiving the intervention, then they will be allocated either to the Internet-delivered intervention or control group.