Diagnosing bipolar disorder and the effect of antidepressants: a naturalistic study

To determine if bipolar disorder is accurately diagnosed in clinical practice and to assess the effects of antidepressants on the course of bipolar illness.

Charts of outpatients with affective disorder diagnoses seen in an outpatient clinic during 1 year (N = 85 with bipolar or unipolar disorders) were reviewed. Past diagnostic and treatment information was obtained by patient report and systematic psychiatric history. Bipolar diagnosis was based on DSM-IV criteria using a SCID-based interview.

Bipolar disorder was found to be misdiagnosed as unipolar depression in 37% of patients who first see a mental health professional after their first manic/hypomanic episode. Antidepressants were used earlier and more frequently than mood stabilizers, and 23% of this unselected sample experienced a new or worsening rapid-cycling course attributable to antidepressant use.

These results suggest that bipolar disorder tends be misdiagnosed as unipolar major depressive disorder and that antidepressants seem to be associated with a worsened course of bipolar illness. However, this naturalistic trial was uncontrolled, and more controlled research is required to confirm or refute these findings.