Examining the clinical correlates of conduct disorder in youth with bipolar disorder.

Background: Conduct Disorder (CD) is highly comorbid with Bipolar Disorder (BP) and this comorbidity is associated with high morbidity and dysfunction. We sought to better understand the clinical characteristics and familiality of comorbid BP + CD by examining children with BP with and without co-morbid CD.

Methods: 357 subjects with BP were derived from two independent datasets of youth with and without BP. All subjects were evaluated with structured diagnostic interviews, the Child Behavior Checklist (CBCL), and neuropsychological testing. We stratified the sample of subjects with BP by the presence or absence of CD and compared the two groups on measures of psychopathology, school functioning, and neurocognitive functioning. First-degree relatives of subjects with BP +/- CD were compared on rates of psychopathology in relatives.

Results: Subjects with BP + CD compared to BP without CD had significantly more impaired scores on the CBCL Aggressive Behavior (p < 0.001), Attention Problems (p = 0.002), Rule-Breaking Behavior (p < 0.001), Social Problems (p < 0.001), Withdrawn/Depressed clinical scales (p = 0.005), the Externalizing Problems (p < 0.001), and Total Problems composite scales(p < 0.001). Subjects with BP + CD had significantly higher rates of oppositional defiant disorder (ODD) (p = 0.002), any SUD (p < 0.001), and cigarette smoking (p = 0.001). First-degree relatives of subjects with BP + CD had significantly higher rates of CD/ODD/ASPD and cigarette smoking compared to first-degree relatives of subjects without CD.

Limitations: The generalization of our findings was limited due to a largely homogeneous sample and no CD only comparison group.

Conclusions: Given the deleterious outcomes associated with comorbid BP + CD, further efforts in identification and treatment are necessary.