Phasic Versus Tonic Irritability: Differential Associations With Attention-Deficit/Hyperactivity Disorder Symptoms.

Abstract

OBJECTIVE\nIrritability is a multifaceted construct in pediatric psychopathology. It has been conceptualized as having a phasic dimension and a tonic dimension. Disruptive mood dysregulation disorder (DMDD) is defined by the presence of both dimensions. Severe irritability, or DMDD, is highly comorbid with attention-deficit/hyperactivity disorder (ADHD). However, it is unknown whether the presence of ADHD modulates the expression of phasic and tonic irritability.\n\n\nMETHOD\nA data-driven, latent variable approach was used to examine irritability and ADHD symptoms in a transdiagnostic pediatric sample (N=489) with primary DMDD, ADHD, subclinical irritability symptoms, or no diagnosis. Using latent profile analyses (LPA), we identified four classes: high levels of both irritability and ADHD symptoms, high levels of irritability and moderate levels of ADHD symptoms, moderate levels of irritability and high levels of ADHD symptoms, and low levels of both irritability and ADHD symptoms. Confirmatory factor analysis operationalized phasic irritability and tonic irritability.\n\n\nRESULTS\nAs expected, the two latent classes characterized by high overall irritability exhibited the highest levels of both phasic and tonic irritability. However, between these two high irritability classes, highly comorbid ADHD symptoms were associated with significantly greater phasic irritability than were moderately comorbid ADHD symptoms. In contrast, the two high irritability groups did not differ on levels of tonic irritability.\n\n\nCONCLUSION\nThese findings suggest that phasic, but not tonic, irritability has a significant association with ADHD symptoms, and that phasic and tonic might be distinct, though highly related, irritability dimensions. Future research should investigate potential mechanisms underlying this differential association.