Chapter 37: Diagnosing Personality Disorders

The DSM-IV-TR operates from a categorical perspective, conceptualizing PDs as inflexible, maladaptive sets of traits that deviate significantly from cultural expectations and result in either functional impairment or subjective distress,. While the provision of specific criteria for the ten officially recognized PDs has aided in increasing inter-rater reliability, clinicians often disagree on which features to consider or what thresholds to apply, and the bases for the diagnostic thresholds themselves are often unexplained,. A major challenge of the categorical system is that most patients present with features of multiple disorders. Consequently, the diagnosis of Personality Disorder Not Otherwise Specified (PDNOS) is frequently provided in clinical settings and empirical studies, applying to individuals with mixed features that together cause clinically significant impairment, even if they fall below the criteria threshold for any one specific disorder. PDNOS can also be used to classify recognized or unofficial disorders that are not included in the main classification, such as sadistic or depressive personality patterns. General diagnostic criteria require determining that the pattern of inner experience and behavior is enduring, inflexible, pervasive, stable, traceable back to adolescence, and leads to significant distress or impairment across areas like cognition, affect, impulse control, or interpersonal functioning. Due to the difficulties clinicians have consistently shown in systematically applying all necessary criteria and achieving reliable diagnoses, structured tools are recommended. Semi-structured interviews and self-report inventories, such as the NEO PI-R, are utilized to ensure comprehensive assessment, identify validity concerns, and offer normative data,. The chapter highlights conceptual issues with the categorical model, noting that it rarely reflects the unclear boundaries observed in clinical reality,. In response, an alternative dimensional framework is discussed, specifically focusing on the Five-Factor Model (FFM) of general personality structure,. The FFM, recognized as the predominant model in various applied fields, organizes personality into five broad, empirically supported domains—Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness—each differentiated into six facets. Research has overwhelmingly established that the FFM comprehensively accommodates and systematically relates to all DSM PDs, providing a robust scientific foundation for construct validity,. Diagnosis using the FFM involves a four-step process: (1) comprehensive assessment of the thirty facets, such as using the NEO PI-R; (2) identifying associated functional impairment and distress; (3) determining if the impairment reaches a clinically significant level, often defined by a score of 60 or below on the DSM-IV-TR’s Axis V; and (4) quantitatively matching the individual's dimensional profile to prototypic profiles of clinical constructs like borderline personality disorder, though the individual’s unique dimensional profile generally offers the optimal description,. This dimensional approach also provides a structured way to describe and study new constructs, like the successful psychopath, that are outside the current official classification.