Borderline and Schizotypal Personality Disorders: Mutually Exclusive or Overlapping?

Abstract

This article is concerned with one aspect of the validity of DSM-III Axis II diagnoses, namely, the discriminability of borderline and schizotypal disorders. Forty-nine patients diagnosed by DSM-III criteria as borderline, schizotypal, or "mixed" personality disorders completed the Borderline Syndrome Index (BSI), an independent self-report 52-item instrument that has been shown to be reliable and to have discriminative validity. A one-way analysis of variance and a discriminant function analysis were conducted. Our major finding was that there were no significant differences among the groups on the BSI self-report test, although there were differences on clinical grounds. We discuss this in terms of "fuzzy set" theory and prototypic systems of classification.