The twofold diagnosis of personality disorder: How do personality dysfunction and pathological traits increment each other at successive levels of the trait hierarchy?

Besides the categorical classification of personality disorders (PDs) in Section II of the DSM-5 (American Psychiatric Association, 2013), which has been transferred as such from DSM-IV, Section III provides an alternative model to stimulate further research on the dimensional conceptualization of PDs. In this alternative system, a PD diagnosis is based on 2 essential criteria: impaired personality functioning and the presence of pathological traits. One topic that warrants further research concerns the incremental validity of these 2 components. The current study addresses this issue in a mixed community-patient sample (N = 233). First, Goldberg's (2006) "bass-ackwards" method was used to examine the hierarchical structure of pathological traits as measured by the Dimensional Assessment of Personality Pathology (DAPP-BQ; Livesley & Jackson, 2009). We then extracted a single higher order factor from the Severity Index of Personality Problems (SIPP-118; Verheul et al., 2008) to derive 1 coherent indicator of personality dysfunction. Correlation and hierarchical regression analyses were used to determine the incremental validity of the dysfunction factor versus the trait components at succeeding levels of the DAPP-BQ hierarchy. The results only partially supported the 2-component PD diagnosis, as traits and dysfunction appeared to have only limited incremental validity. Moreover, lower order traits were generally unable to outperform higher order components in predicting specific DSM-IV PDs. Implications for the conceptualization and assessment of personality pathology are discussed. (PsycINFO Database Record