Differential outcomes of tonic and phasic irritability in adolescent girls

Background: Irritable mood is a transdiagnostic clinical feature that is present in multiple psychiatric disorders. Although irritability is frequently examined as a unitary construct, two dimensions of irritability, tonic (i.e., irritable mood) and phasic (i.e., temper outbursts), have been hypothesized. However, few studies have examined whether tonic and phasic irritability are empirically separable and predict different forms of psychopathology. Methods: We utilized data from a longitudinal study of a community sample of 550 girls (age 13.5–15.5 years) followed at 9-month intervals for 3 years. We conducted exploratory factor analysis (EFA) using items from three self-report inventories: the International Personality Item Pool Anger scale, Temperament and Affectivity Inventory Anger scale, and Buss-Perry Aggression Questionnaire Anger scale. Results: The EFA identified dimensions that were consistent with tonic and phasic irritability. Tonic irritability at baseline independently predicted the development of depressive disorders and generalized anxiety disorder (GAD) in subsequent waves. Phasic irritability independently predicted a decreased probability of GAD, but an increased probability of oppositional defiant, conduct, and substance use disorder, and greater risky sexual behavior and relational aggression during the follow-up. Conclusions: Tonic and phasic irritability appear to be separable constructs with unique implications for later psychopathology and related behavior among adolescent girls. It is important to consider this distinction in research on the etiology and pathophysiology of irritability and developing effective treatments.