Borderline personality disorder and the misdiagnosis of bipolar disorder

Recent reports suggest bipolar disorder is not only under-diagnosed but may at times be over-diagnosed. Little is known about factors that increase the odds of such mistakes. The present work explores whether symptoms of borderline personality disorder increase the odds of a bipolar misdiagnosis. Psychiatric outpatients (n = 610) presenting for treatment were administered the Structured Clinical Interview for DSM-IV (SCID) and the Structured Interview for DSM-IV Personality for DSM-IV axis II disorders (SIDP-IV), as well as a questionnaire asking if they had ever been diagnosed with bipolar disorder by a mental health care professional. Eighty-two patients who reported having been previously diagnosed with bipolar disorder but who did not have it according to the SCID were compared to 528 patients who had never been diagnosed with bipolar disorder. Patients with borderline personality disorder had significantly greater odds of a previous bipolar misdiagnosis, but no specific borderline criterion was unique in predicting this outcome. Patients with borderline personality disorder, regardless of how they meet criteria, may be at increased risk of being misdiagnosed with bipolar disorder.