Is the distinction between tonic and phasic irritability meaningful in 3-year-old children?

Irritability encompasses both normative misbehavior in early childhood and clinically significant problems across development. Recent studies have distinguished between tonic (i.e., persistently angry or grumpy mood) and phasic (i.e., temper tantrums or outbursts) forms of irritability and shown that they have different implications for psychopathology and functioning. However, data on this distinction in young (i.e., preschool aged) children are nonexistent. We utilized data from a longitudinal study of a community sample of 462 3-year-olds followed to age 15. We conducted confirmatory factor analysis (CFA) using items from a diagnostic interview and several parent-report inventories and examined concurrent and prospective associations with clinically relevant variables. The CFA identified dimensions consistent with tonic and phasic irritability. Tonic irritability was independently associated with concurrent parent-reported temperamental negative affectivity and surgency, and depressive and oppositional defiant (ODD) disorders, and predicted higher rates of disruptive behavior disorders (DBD) and suicidal behavior in later childhood and adolescence. Phasic irritability was independently associated with concurrent laboratory observations of child impulsivity, parent-reported temperamental negative affectivity, surgency, and low effortful control, maladaptive parenting, and generalized anxiety disorder (GAD), attention-deficit hyperactivity disorder (ADHD), and ODD, but it did not predict later psychopathology. Tonic and phasic irritability are separable in 3-year-old children, but their correlates and outcomes are not as distinct as in older youth. This may reflect the greater difficulty characterizing normative and pathological irritability in the preschool period.