CONCLUSIONS: Although irritability appears to be transdiagnostic, phenotypically, it was most strongly associated with headstrong/hurtful ODD items and broader behavioural problems, which favours the ICD-11 approach of including irritability as a specifier of ODD. However, irritability appeared to be a key connector between both ADHD and behavioural problems to depression; thus, is important to monitor and treat in affected youth with ADHD or behavioural problems.
