Editorial: The Boundaries of Irritability and Implications for Measurement

Irritability is a defining feature or symptom in at least 15 DSM-5 disorders,¹ and this does not even account for many more disorders that commonly co-occur with irritability. However, just as the transdiagnostic nature of irritability supports its unequivocal importance in child mental health, it also contributes to criticisms that it is "ubiquitous."² How to conceptualize the role of irritability in psychopathology rests on our ability to define it and its boundaries. Unfortunately, there is a lack of consensus on the definition of irritability. In fact, how to disentangle irritability's mood and behavioral components has been described as one of the biggest challenges related to irritability research.³ This editorial is a commentary on Zik et al.'s⁴ study, which takes an emprical approach to determine the overlap between questionnaire measures of irritability, anger, and aggression, thereby informing our conceptualization of irritabiltiy and focusing attention on critical measurement issues such as the impact of informant.