Differentiating borderline personality from bipolar disorder with the Mood Disorder Questionnaire (MDQ): A replication and extension of the International Mood Network (IMN) Nosology Project

IntroductionVöhringer et al. identified a triad of items on the Mood Disorder Questionnaire (MDQ) that best discriminated between borderline personality disorder (BPD) and bipolar disorder (BD) in a tertiary mood clinic setting 23]. The present study aimed to replicate and extend these findings by examining the performance of the triad across a range of cut-off scores and comparing the operating characteristics of the triad to the full MDQ.MethodsPatients presenting for treatment were assessed with the Structured Clinical Interview for DSM-IV (SCID) and the BPD module of the Structured Interview for DSM-IV Personality (SIDP-IV). The present report is based on 476 depressed patients who had a principal diagnosis of major depressive disorder or BD and who completed the MDQ.ResultsFifty-seven patients were diagnosed with BD and fifty-four patients were diagnosed with BPD. Both the triad and full MDQ significantly predicted BD diagnosis (p < .001), but the triad had optimal operating characteristics, particularly at a cut-off of two.ConclusionWithin a sample of depressed patients, the MDQ triad is a better screener for BD than the full MDQ, particularly if a positive triad screen is indicated by the presence of any two items. The triad is particularly good for differentiating between BD and BPD, whereas the full MDQ does a poorer job of differential diagnosis. Future studies should administer the triad as a stand-alone scale.