Objective: To present nationally representative data on 12-month and lifetime prevalence, correlates, and comorbidity of bipolar I disorder.
Method: The data were derived from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (N = 43,093). Prevalences and associations of bipolar I disorder with sociodemographic correlates and Axis I and II disorders were determined.
Results: Prevalences of 12-month and lifetime DSM-IV bipolar I disorder were 2.0% (95% CI = 1.82 to 2.18) and 3.3% (95% CI = 2.76 to 3.84), respectively, and no sex differences were observed. The odds of bipolar I disorder were significantly greater among Native Americans, younger adults, and respondents who were widowed/separated/divorced and of lower socioeconomic status and significantly lower among Asians and Hispanics (p < .05). Men were significantly (p < .05) more likely to have unipolar mania and earlier onset and longer duration of manic episodes, while women were more likely to have mixed and major depressive episodes and to be treated for manic, mixed, and major depressive episodes. Bipolar I disorder was found to be highly and significantly related (p < .05) to substance use, anxiety, and personality disorders, but not to alcohol abuse.
Conclusion: Bipolar I disorder is more prevalent in the U.S. population than previously estimated, highlighting the underestimation of the economic costs associated with this illness. Associations between bipolar I disorder and Axis I and II disorders were all significant, underscoring the need for systematic assessment of comorbidity among bipolar I patients.