Personality disorder dysfunction versus traits: structural and conceptual issues.

As it stands now, the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, in press) will maintain the categorical model and criteria distinguishing the 10 personality disorders (PDs) described in the fourth edition of the manual (DSM-IV; American Psychiatric Association, 1994). An alternative diagnostic proposal based on two criteria, being impaired personality functioning and the presence of maladaptive traits, will be referred to a special section for further research and clinical evaluation. Two issues pertaining to this alternative diagnostic approach need further clarification. First, more insight is required in the specific nature of personality dysfunction, its underlying structure, and optimal operationalization. Second, confusion still exists about how personality dysfunction and traits are interconnected and how they both contribute to the PD diagnosis. The current study addresses both issues empirically in a sample of 159 psychiatric patients by (a) investigating the structure of personality functioning as assessed by the Severity Indices of Personality Problems (SIPP-118), and (b) determining the incremental validity of the resulting dysfunction factors vis-à-vis trait domains (measured by the NEO Personality Inventory-Revised [NEO-PI-R]) in explaining DSM-IV PD variance. Trait and dysfunction dimensions were strongly correlated but showed significant, though limited, incremental validity above each other. Implications for the conceptualization of personality pathology are discussed.