Decreasing heterogeneity in oppositional defiant disorder and early-onset conduct disorder: Potential subtypes, external validators, and diagnostic implications

Although the polythetic list of symptoms used within many DSM categories permits some flexibility in assigning individuals to diagnostic categories, this strategy can lead to a great deal of heterogeneity within diagnostic categories. This approach is particularly problematic for oppositional defiant disorder (ODD) and conduct disorder (CD), which are closely related in taxonomic and developmental terms and often considered concurrently. ODD and CD co-occur with many additional psychological conditions, such as attention-deficit/hyperactivity disorder, mood disorders, anxiety disorders, and substance use disorders. Given this within-category heterogeneity and high rates of disorder co-occurrence, identification of meaningful subtypes within the ODD and CD categories is important. We provide evidence for two potential subtypes of ODD: one that is characterized by the emotional symptoms of ODD and a second that is characterized primarily by the behavioral symptoms of ODD. We also consider the DSM specifiers of childhood- and adolescent-onset CD. We examine evidence for potential correlates or candidate processes that may be relevant to these subtypes, thus providing a preliminary framework for testing the construct validity of these subtypes. These potential processes include temperamental features, emotion regulation, callous-unemotional traits, proactive and reactive aggression, autonomic activity, executive functioning, affective decisionmaking, and limbic system functioning. We present a testable model linking these candidate processes and symptom subtypes. We provide implications of this model for decreasing within-class heterogeneity and thus informing the next version of the DSM, as well as implications for research efforts aimed at ODD and CD.