An Elaborated Model of Youth Externalizing Psychopathology

Externalizing is an integral spectrum in hierarchical dimensional models of psychopathology. Comprehensive models of Externalizing have been developed for late adolescents and adults, but not for youth. We developed and characterized an elaborated model of youth Externalizing psychopathology using item response theory and confirmatory factor analyses of ADHD, ODD, and CD symptoms to investigate the psychometric properties of Externalizing’s components. Participants included large population-representative twin and clinic-referred samples of youth. Using several criteria, increasingly elaborated models comprising an Externalizing dimension and seven fine-grained symptom factors outperformed models containing omnibus ADHD, ODD, and CD symptom dimensions. Results replicated across clinic and twin samples, with the Externalizing dimension most strongly reflecting defiant behavior. Symptom domains varied in their measurement properties across levels of Externalizing. This elaborated model of youth Externalizing sets the stage for future investigations of causes and outcomes, and for examining measurement invariance across individuals of diverse backgrounds.