Can a subtype of conduct disorder linked to bipolar disorder be identified? Integration of findings from the Massachusetts General Hospital Pediatric Psychopharmacology Research Program.

Our intent was to investigate systematically the overlap between conduct disorder (CD) and bipolar disorder (BPD). We hypothesized that neither CD nor manic symptoms were secondary to the other disorder and that children with the two disorders would have correlates of both. Results from a series of programmatic studies examining phenotypic features of bipolar and conduct disorder alone or combined in probands and relatives were evaluated within and without the context of ADHD. Examination of the clinical features, patterns of psychiatric comorbidity, functioning in multiple domains, and familiality showed that children with CD and BPD had similar features of each disorder irrespective of the comorbidity with the other disorder. Our data suggest that when BPD and CD co-occur in children, both are correctly diagnosed. In these comorbid cases, CD symptoms should not be viewed as secondary to BPD, and manic symptoms should not be viewed as secondary to CD.