Borderline disorders--the validity of the diagnostic concept.
Reliable concepts of borderline disorders are a prerequisite for studies of validity. Gunderson's and DSM-III's definition of Borderline personality disorder (BPD) and DSM-III's definition of Schizotypal personality disorder (SPD) fulfill these demands. The empirical evidence for descriptive, construct and predictive validity of these disorders is presented and discussed. The review concludes that BPD has descriptive validity but lacks the 2 other stronger types of validity. SPD has both descriptive and construct validity but lacks predictive validity. Various strengths and weaknesses of the empirical studies of these borderline concepts are discussed.