Despite its widespread use, the DSM-IV Personality Disorder (PD) diagnoses dissatisfied a large number of both prominent clinicians and researchers. This dissatisfaction seems to stem from psychometric or taxometric flaws of PD diagnoses, which lead to the current debate on the need for a dimensional assessment of PD in the next DSM-V. It was quite surprising to observe that the central issue of the usefulness of the current PD diagnoses – regardless of their dimensional or categorical structure – to plan and administer treatment (which represents the application-oriented aspect of the state of our advancing knowledge on PDs) has been rarely addressed in the current debate.

The presentation will focus on a review of the published literature as well as on empirical data.

The link between the ambiguity of the DSM-IV PD diagnostic system and many of the psychometric/taxometric flaws will be presented. The fact of unsufficient research data on several PDs to enter evidence-based changes in the DSM-V will also be discussed. The unresolved controversies between hypothesized dimensional structures and etiological models of PDs, as well as the lack of evidence that shifting to a dimensional model will increase the usefulness of PD diagnoses to treat PD patients will also be presented. Finally, a mixed model, based both on PD core features and similarity to prototype will be presented in the light of maximizing clinical (and research) usefulness.