Refining the phenotype of borderline personality disorder: Diagnostic criteria and beyond.

Borderline personality disorder (BPD) is a heterogeneous disorder, and previous analyses have parsed its phenotype in terms of subtypes or underlying traits. We refined the BPD construct by testing a range of latent variable models to ascertain whether BPD is composed of traits, latent classes, or both. We also tested whether subtypes of BPD could be distinguished by anger, aggressiveness, antisocial behavior, and mis-trustfulness, additional putative indicators drawn from Kernberg's (1967, 1975) theory of BPD. In a mixed clinical and nonclinical sample (N = 362), a factor mixture model consisting of two latent classes (symptomatic and asymptomatic) and a single severity dimension fit the BPD criteria, as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), data better than latent class or factor analytic approaches. In the second analytic phase, finite mixture modeling of the symptomatic latent class (n = 100) revealed four BPD subtypes: angry/aggressive, angry/mistrustful, poor identity/low anger, and prototypical. Our results support a hybrid categorical-dimensional model of the BPD DSM-IV criteria. The BPD subtypes emerging from this model have important implications for treatment and etiological research.