Differentiation of the bipolar disorders from borderline personality disorder

Aims: Firstly, to identify a set of clinical variables that differentiates the bipolar disorders (BPs) from borderline personality disorder (BPD). Secondly, to examine the pan-diagnostic feature of emotional dysregulation. Thirdly, to examine the impact of differing diagnostic criteria on the capacity to differentiate the two conditions. Methods: Two hundred and twenty-six participants aged 18 years and older with a prior diagnosis of BP, BPD or both were recruited from several metropolitan clinical services. Diagnostic allocation was made on the basis of DSM-IV criteria and by clinical judgment. Participants undertook a diagnostic interview and completed self-report measures. Study I compared BP vs BPD across clinical variables; Study II compared emotional dysregulation between BP vs BPD vs comorbid BP/BPD; and Study III compared clinical vs DSM diagnoses of the three diagnostic categories. Results: Study I found predictors of BPD status (as against BP) varied according to diagnostic decisions, with the most consistent items being childhood sexual abuse, childhood depersonalization, personality variables relating to relationship difficulties and sensitivity to criticism, and the absence of a BP family history. Study II found greatest impairment in emotion regulation strategies in the comorbid group followed by the BPD and then the BP groups. Adaptive emotion regulation strategies were superior in the bipolar group, without significant differences between the comorbid and BPD groups. Study III found clinician vs DSM concordance rates were reduced as BP disorder duration criteria were relaxed, with discordance mainly arising from clinical allocation of a BP disorder for those DSM assigned as having unipolar depression. Rates of BPD allocation varied marginally, with discordance mostly arising from those so clinically diagnosed receiving a comorbid BP/BPD DSM diagnosis. DSM overestimated their comorbid prevalence compared to clinician diagnoses. Not imposing the minimum DSM duration criteria for BP hypo/mania did not increase the prevalence of misdiagnosing BPD. Conclusions: Findings reveal that using the identified clinical features, BPD can be differentiated from BP with a high degree of accuracy and those with BP, BPD and comorbid BP/BPD show differing patterns of emotion regulation. Differing prevalence estimates and reasons for discordant DSM and clinician diagnoses should assist clinical decision-making