We conducted some initial exploration of whether categorical diagnoses of ODD could be sub-typed on the basis of irritable and headstrong symptoms. Using current diagnostic guidelines this was far from straightforward. Cases of ODD purely involving irritability cannot exist with a four symptom diagnostic threshold, and cases with only headstrong symptoms were exceedingly rare. In practice, most youth who met criteria for ODD showed a mix of these two symptom patterns. Person-centered approaches such as latent class analyses might provide a complimentary perspective to our findings and more complex approaches to sub-typing warrant further investigation. For example the recent DSM-V proposal for Temper Dysregulation Disorder with Dysphoria (TDD, DSM-5 Childhood and Adolescent Disorders Work Group, 2010) would identify the most irritable cases of ODD as suffering a mood disorder. The links found here and elsewhere between irritability and affective disorder are consistent with the suggested mood diagnosis. Further research will be required to identify whether the correlates and outcomes of TDD differ from the current specification of ODD and to identify the clinical characteristics of children with ODD who do
