Different routes to the same destination? Comparing Diagnostic and Statistical Manual of Mental Disorders, fifth edition Section II- and alternative model of personality disorder-defined borderline personality disorder.

Borderline personality disorder (BPD) is defined by the presence of at least five of nine symptoms in Section II of the Diagnostic and Statistical Manual of Mental Disorders, fifth edition. In the Diagnostic and Statistical Manual of Mental Disorders, fifth edition, Section III Alternative Model of Personality Disorders (AMPD), BPD is defined by deficits in self and/or interpersonal functioning (Criterion A), elevated negative affectivity, and elevated antagonism and/or disinhibition (Criterion B). However, it is unclear if these definitions describe the same people and if the AMPD criteria explain unique variability in treatment outcomes in this population. In a treatment-seeking sample of adult participants diagnosed with BPD according to Section II criteria (n = 65, M_age = 27.60, 70.8% female, 76.9% White), we found a majority (66.2%) would have also received the diagnosis based on AMPD criteria. Those meeting AMPD criteria reported more severe Section II BPD symptoms than those who did not, ps < .02, ds > 0.60, and the presence or severity of Section II fears of abandonment and inappropriate anger uniquely predicted AMPD BPD diagnoses, ps < .03, ORs ≥ 2.31. Changes in AMPD dimensions explained 34% of the variability in change in work/social adjustment (p = .13) and quality of life (p = .22), respectively, over and above changes in Section II symptoms during a novel cognitive-behavioral treatment for BPD. These results suggest that AMPD criteria capture a more severe subset of BPD than Section II criteria and may be important predictors of treatment outcomes. We discuss the potential trade-offs of this shift in diagnosis.