Is bipolar disorder overdiagnosed among patients with substance abuse?

Background: Bipolar illness is frequently misdiagnosed. Several studies have focused on the underdiagnosis of this condition and the frequent long delay in its recognition. However, the illness is difficult to diagnose and many of its symptoms are shared by other conditions. In order to determine the accuracy of the diagnosis of bipolar illness among subjects with substance abuse, we carried out a study in patients with a previous diagnosis of bipolar disorder (BD) and known history of substance abuse or dependence, who were currently engaged in treatment for substance abuse. Methods:Individuals participating in a community-based substance treatment program and who had a previous diagnosis of BD were invited to undergo a structured clinical interview for diagnosis performed by a psychiatrist. In addition to the interview, previous hospital records were reviewed whenever possible. Diagnosis was made following strict DSM-IV criteria. Results:Only 9 of 21 (42.9%) subjects met diagnostic criteria for BD. Seven were BD type II and two were BD I. Conclusions:Bipolar disorder is frequently misdiagnosed following strict DSM-IV criteria. Among subjects with substance abuse, it may be overdiagnosed by psychiatrists.