Simplifying profiles of comorbidity in bipolar disorder

Background: Comorbid psychiatric symptoms in bipolar disorder (BD) predict poorer course of illness and treatment outcome. The sheer number of comorbid symptoms has thwarted developing treatments to address these comorbid concerns. The goal of this study was to develop a more parsimonious approach to understanding clusters of comorbid symptoms within BD. Method: Data were collected as part of the National Epidemiologic Survey on Alcohol and Related Conditions. Structured diagnostic interviews were conducted with 43,093 participants using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV (AUDADIS-IV). Analyses were conducted on lifetime symptom counts for the most common 14 comorbid disorders among the 1411 persons who met lifetime criteria for bipolar I disorder. Results: An exploratory factor analysis with promax rotation as well as confirmatory factor analyses revealed a three-factor solution of Externalizing, Anxiety, and Mood syndromes, with a higher order Internalizing factor comprised of the Mood and Anxiety factors. Limitations: Further research is needed in a clinical sample. Conclusions: Comorbid symptoms in BD tend to cohere into Internalizing and Externalizing disorders, which could simplify research and treatment on comorbidity in BD.