Precursors are evoked upstream of the Capgras’ syndrome. Then, an analogy is suggested between the need for prognostic classification linked to the saturation of the asylum population at the dawn of the 20th century, and the current overflow of the psychiatric healthcare system. The contemporary situation justifies the search for information useful to mitigate ill mental health in at-risk adolescents. The article presents recent research reports on adolescents at-risk of emotional dysregulation, stemming from a longitudinal cohort database of European adolescents. The database analyses have revealed new brain and psychometric predictors of emotional dysregulation in adolescents. New early indicators were derived from easy-to-administer questionnaires, exploring emotions, affective symptoms and traits, sleep, early adversity and stress, puberty. Findings suggest that the physiology and stages of brain development could be taken into account for decisions regarding Mental Health. Studies on adolescent brain development have implications for public health, in terms of the age of protection for adolescents, and targeted prevention upstream of care.