Recent data indicate that bipolar illness is underdiagnosed and therefore undertreated in the community (Slide 1). A recent survey of >85,000 households in the United States found a 3.7% positive screen for prominent bipolar symptomatology. Using the Mood Disorder Questionnaire, which has good specificity and sensitivity in outpatient clinics, the study also found that the prevalence was higher, 9.3%, among patients 18–24 years of age. However, most disappointing was that only 20% of the positive screens were diagnosed as bipolar, and among those, most were not treated with mood stabilizers. In addition, 31% of patients had been diagnosed with unipolar depression. Several studies have shown that approximately 20% to 40% of presumptively unipolar patients actually have bipolar II or bipolar disorder not otherwise specified. Combined, the data show that bipolar disorder, bipolar depression in particular, is highly prevalent and often misdiagnosed or unrecognized.

Two recent studies found virtually the same data showing that depression is the predominant problem in naturalistically treated bipolar outpatients. Judd and colleagues found that depression was three times more prevalent than mania in bipolar patients. This is exactly what was found in the Stanley Foundation bipolar outpatient follow-up study, which rated the study's first 258 patients every day for 1 year (Slide 2). The study found that patients were ill almost 50% of the time; they were depressed 33% of the days in the year, and hypomanic or manic 10.8% of the days. This occurred despite aggressive treatment with a variety of agents, such as mood stabilizers, antidepressants, and benzodiazepines in 50% of the patients, and typical or atypical neuroleptics in almost 50% of the patients. Thus, even bipolar patients who are intensively treated in academic settings have a very substantial degree of morbidity, particularly depression.