Attention-deficit/hyperactivity disorder (ADHD) frequently co-occurs with oppositional and conduct-related behavioural difficulties, raising questions about how these symptoms are structurally related within clinically diagnosed youth. Dimensional models of psychopathology, such as the Hierarchical Taxonomy of Psychopathology (HiTOP), conceptualize these behaviours as part of a broader externalizing spectrum characterized by shared patterns of behavioural dysregulation. However, empirical…
