Bipolar disorder and comorbid conduct disorder in childhood and adolescence

To report on the rate and associated features of comorbid conduct disorder (CD) in 26 bipolar (BP) youths and examine whether comorbidity affects clinical course.

The clinically referred subjects, 8 to 13 years old at study entry, were participating in a longitudinal investigation of childhood-onset psychiatric disorders. They were repeatedly examined during an interval of up to 12 years, and diagnosed by DSM-III criteria.

There was a 69% rate of lifetime comorbidity and 54% rate of episode comorbidity with CD. CD predated the first BP episode for 11 youths and postdated it for 7. Only 12% of the 26 children had primary uncomplicated affective illness. Youngsters without CD comorbidity had a higher rate of primary affective illness, a somewhat greater number of BP episodes, but slightly better overall clinical course. They also had a greatly elevated rate of maternal mania, whereas BP youths with CD were notable for the rate of paternal substance abuse.

Comorbid CD may exist in a large portion of young patients with BP disorder, confusing its clinical presentation and possibly accounting for some of the documented failure to detect BP disorder. Comorbid CD in bipolar youths appears to be associated with a somewhat worse clinical course. The overall indications are that comorbid CD may identify a subtype of very early onset BP disorder.