Childhood Irritability: Predictive Validity and Mediators of Adolescent Psychopathology.

Despite its transdiagnostic significance, there is modest evidence with respect to the predictive validity of childhood irritability, especially across developmental periods; similarly, little is known about explanatory factors underlying these predictions. This study had two goals: (1) to test the predictive validity of childhood irritability with respect to adolescent internalizing and externalizing problems, controlling for baseline ADHD and related psychopathology and (2) to test theoretically-derived family (i.e., parenting behavior, parenting stress) and social (i.e., peer status, social skills) constructs as explanatory factors of adolescent psychopathology. Two hundred thirty ethnically diverse (51.5% White) 5-10-year-old youth (32% female) with (n = 121) and without (n = 110) ADHD completed three separate laboratory-based assessments across six to seven years. Temporally-ordered predictors, putative mediators, and psychopathology outcomes were assessed using multiple informants (i.e., parent, teacher, youth) and methods (i.e., structured interviews, normed rating scales). Controlling for demographic factors, clinical correlates, and baseline psychopathology, childhood irritability uniquely predicted adolescent externalizing problems, but not internalizing problems. Next, analyses revealed that low social skills partially explained predictions of adolescent internalizing problems. However, family or social factors did not underlie predictions of adolescent externalizing problems. These preliminary findings support the predictive validity of childhood irritability with respect to early adolescent externalizing problems and implicate low social skills as a potentially unique mediator of internalizing outcomes. Intervention-induced improvements in social skills may minimize emergent psychopathology initiated by significant childhood irritability.