An overview of issues related to categorical and dimensional models of personality disorder assessment

Despite long-standing efforts to improve the current diagnostic system for Axis II, problems remain with the categorical conceptualization of personality disorders (PDs). Due in part to these problems, interest has developed in dimensional models of PD classification. In this article, we discuss four issues relevant to categorical vs. dimensional assessment of PDs: (a) problems with self-reports in PD patients, (b) methodological issues in behavioral and clinician assessment of PDs, (c) challenges that arise when dimensional models are applied to patient and nonpatient samples, and (d) clinical implications of categorical and dimensional PD models. We suggest that researchers and clinicians address these concerns to avoid implementing a new PD assessment model that-although different from the current system-would otherwise remain fraught with difficulties.     

A dimensional model of personality disorder: incorporating DSM Cluster A characteristics

The authors articulate an expanded dimensional model of personality pathology to better account for symptoms of DSM-defined Cluster A personality disorders. Two hundred forty participants (98 first-degree relatives of probands with schizophrenia or schizoaffective disorder, 92 community control participants, and 50 first-degree relatives of probands with bipolar disorder) completed a dimensional personality pathology questionnaire, a measure of schizotypal characteristics, and Chapman measures of psychosis proneness. Scales from all questionnaires were subjected to an exploratory factor analysis with varimax rotation. A 5-factor structure of personality pathology emerged from the analyses, with Peculiarity forming an additional factor to the common 4-factor structure of personality pathology (consisting of Introversion, Emotional Dysregulation, Antagonism, and Compulsivity). These results support a 5-factor dimensional model of personality pathology that better accounts for phenomena encompassed by the Cluster A personality disorders in DSM-IV-TR (4th ed., text revised; American Psychiatric Association, 2000). This study has implications for the consideration of a dimensional model of personality disorder in DSM-V by offering a more comprehensive structural model that builds on previous work in this area.     

Categorical versus dimensional status of borderline personality disorder

One of the many controversies concerning the borderline personality disorder (BPD) diagnosis is whether the construct refers to a categorical or dimensional variable. The current study used Meehl's (1973) maximum covariance analysis to investigate this issue. The charts of 409 psychiatric inpatients were systematically reviewed for the presence of BPD and dysthymic symptoms. Charts of 244 inpatients were also reviewed to assess the presence of indicators of male sex, a categorical variable. The results for BPD and dysthymia were consistent with a dimensional model, whereas those for male sex were consistent with a categorical model. A dimensional model of classification of BPD is recommended, and suggestions for future research are provided.     

Behavioral and molecular genetic contributions to a dimensional classification of personality disorder

This article examines the possible contribution of behavioral and molecular genetic research to the development of a dimensional classification of personality disorder. It is argued that the results of molecular studies are too preliminary to have immediate nosological significance. However, behavioral genetic methods could play a useful role in constructing a classification that reflects the genetic architecture of personality disorder. It is also argued that the best approach to constructing a valid classification would be to integrate behavioral genetic methods with the construct validation framework used in test construction. An integrative approach is proposed that seeks to combine constructs from alternative dimensional models. It is suggested that strong evidence of a four-dimensional structure to personality disorder provides a way to organize a preliminary model. An initial set of primary traits to define these secondary domains would then be compiled from existing models and refined using a combination of traditional psychometric analyses and behavioral genetic methods. It is concluded that an etiologically based classification is feasible for the DSM-V.     

Alternative dimensional models of personality disorder: finding a common ground

The recognition of the many limitations of the categorical model of personality disorder classification has led to the development of quite a number of alternative proposals for a dimensional classification. The purpose of this article is to suggest that future research work toward the integration of these alternative proposals within a common hierarchical structure. An illustration of a potential integration is provided using the constructs assessed within existing dimensional models. Suggestions for future research that will help lead toward a common, integrative dimensional model of personality disorder are provided.     

The DSM-5 dimensional model of personality disorder: rationale and empirical support

Ideally, a dimensional model of normal and abnormal personality functioning within the forthcoming DSM-5 would represent a common ground among the existing alternative models and would be consistent with the substantial body of empirical research that has accumulated on such models. The DSM-5 Work Group had the opportunity to make an historic step toward the integration of the normal personality traits researched within psychology with the personality disorders of psychiatry. They chose instead to construct a cumbersome six-dimensional model of personality disorder that excludes normal personality traits, is inconsistent with the preponderance of the research, and is distinguished explicitly from the predominant dimensional model of general personality structure.     

Personality profiles and the prediction of categorical personality disorders

Personality disorders (PDs) are usually construed as psychiatric categories characterized by a unique configuration of traits and behaviors. To generate clinical hypotheses from normal personality trait scores, profile agreement statistics can be calculated using a prototypical personality profile for each PD. Multimethod data from 1,909 psychiatric patients in the People's Republic of China were used to examine the accuracy of such hypotheses in the Interpretive Report of the Revised NEO Personality Inventory. Profile agreement indices from both self-reports and spouse ratings were significantly related to PD symptom scores derived from questionnaires and clinical interviews. However, accuracy of diagnostic classification was only modest to moderate, probably because PDs are not discrete categorical entities. Together with other literature, these data suggest that the current categorical system should be replaced by a more comprehensive system of personality traits and personality-related problems.     

A categorical and dimensional perspective on depression within a nonclinical sample of couples

The present study investigated the role of psychosocial variables that are indicators for depressive symptomatology within a couple. The variables chosen for this study were conflict communication, marital adjustment, attachment, attribution style, and personality traits--all potentially specific indicators. A global factor analysis on all our measures revealed that our individual and relational measures were stable findings. We wanted to compare a dimensional and categorical view of depression. First, we focused on the total nonclinical sample, considering depression on a continuum, and studying the selected characteristics along with the varying degree of depressive complaints. The results highlighted the importance of individual characteristics (neuroticism and life satisfaction) covarying with the level of depressive symptomatology in the nonclinical sample (n = 186 couples). Second, in addition to this correlational design, we compared the group of most depressed subjects and their partners with a control sample (n = 34). Both approaches pointed to the same conclusion: individual characteristics covaried with mild depression, whereas couple characteristics only came into the picture with a higher level of depressive complaints. The lowest levels of depressive complaints were associated with individual co-morbidity only, whereas increasing complaints went along with additional relational complaints. Implications for assessment and future research are discussed.     

Systema Temporis: A time-based dimensional framework for consciousness and cognition

This study uses a combined categorical-dimensional approach to depict a hierarchical framework for consciousness similar to, and contiguous with, factorial models of cognition (cf., intelligence). On the basis of the longstanding definition of time consciousness, the analysis employs a dimension of temporal extension, in the same manner that psychology has temporally organised memory (i.e., short-term, long-term, and long-lasting memories). By defining temporal extension in terms of the structure of time perception at short timescales (<100 s), memory and time consciousness are proposed to fit along the same logarithmic dimension. This suggests that different forms of time consciousness (e.g., experience, wakefulness, and self-consciousness) are embedded within, or supported by, the ascending timescales of different modes of memory (i.e., short-term, long-term, etc.). A secondary dimension is also proposed to integrate higher-order forms of consciousness/emotion and memory/cognition. The resulting two-dimensional structure accords with existing theories of cognitive and emotional intelligence.     

Integrated treatment: a conceptual framework for an evidence-based approach to the treatment of personality disorder

Evidence that various therapies are effective in treating personality disorder and that outcome does not differ substantially across treatments suggests that it is time replace concerns about the efficacy of specific therapies and which form of therapy to use with an evidence-based approach that combines methods that work from all therapies. A framework is proposed for selecting and combining eclectic treatment methods and delivering them in a coordinated way. The framework has two components: (1). a system for conceptualizing personality disorder based on empirical knowledge about the structure, etiology, development, and stability of personality pathology to use as a guide to selecting interventions and planning the sequence in which they will be used; and (2), a model of therapeutic change based on the general literature on psychotherapy outcome and specific studies of PD treatments. The framework proposes that integrated treatment be organized around general principles of therapeutic change common to all effective therapies supplemented with more specific treatment methods taken from the different therapies as needed to tailor treatment to individual patients and treat specific problems and psychopathology. The coordinated delivery of such a diverse array of interventions is achieved by using a phases of treatment scheme that proposes that treatment focus on specific symptoms and problems is a systematic and orderly way according to their stability and potential for change.     

A framework for profile similarity: integrating similarity, normativeness, and distinctiveness

Many questions in personality psychology lend themselves to the analysis of profile similarity. A profile approach to issues such as personality judgment, personality similarity, behavioral consistency, developmental stability, and person-environment fit is intuitively appealing. However, it entails conceptual and statistical challenges arising from the overlap among profile similarity and normativeness, which presents potential confounds and potential opportunities. This article describes the normativeness problem, articulating the need to evaluate profile similarity alongside normativeness and distinctiveness. It presents conceptual and psychometric foundations of a framework differentiating these elements for pairs of profiles. It derives two models from this framework, and it discusses the application of their components to a variety of research domains. Finally, it presents recommendations and implications regarding the use of these components and profile similarity more generally. This approach can reveal and manage potential confounds, and it can provide theoretical insights that might otherwise be overlooked.     

Plate tectonics in the classification of personality disorder: shifting to a dimensional model

The diagnostic categories of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders were developed in the spirit of a traditional medical model that considers mental disorders to be qualitatively distinct conditions (see, e.g., American Psychiatric Association, 2000). Work is now beginning on the fifth edition of this influential diagnostic manual. It is perhaps time to consider a fundamental shift in how psychopathology is conceptualized and diagnosed. More specifically, it may be time to consider a shift to a dimensional classification of personality disorder that would help address the failures of the existing diagnostic categories as well as contribute to an integration of the psychiatric diagnostic manual with psychology's research on general personality structure.     

A taxometric study of borderline personality disorder

Taxometric methodology was used to determine whether borderline personality disorder (BPD) represents a taxon that is categorically distinct from normal personality or whether it falls on a dimensional continuum with normality. Two taxometric procedures were used with a sample of 1,389 outpatients assessed for BPD symptoms by semistructured interview. The procedures indicated that BPD does not represent a latent category. Implications are drawn for the conceptualization and etiology of BPD, and for the categorical versus dimensional status of personality disorders in general.     

Conduct disorder and personality

A sample of children with a diagnosis of conduct disorder and a sample of children from a London comprehensive school were investigated. Three questionnaires were administered to assess personality, impulsiveness and anxiety. Of the personality measures contained within the Junior Eysenck Personality Questionnaire only Psychoticism was found to significantly differentiate the conduct disorder and normal control samples. The Impulsiveness scale of the I₆ also differentiated the two samples. There were no significant differences between the two samples in their scores on the anxiety scale of the “What I Think and Feel”. The findings are discussed in relation to theories of personality proposed by Eysenck and Eysenck (1969), Gray (1987) and Quay (1988).     

Clinical utility of dimensional models for personality pathology

Clinical utility is defined as the extent to which the DSM assists clinical decision makers in fulfilling the various clinical functions of a psychiatric classification system. Distinction is made between elements of diagnostic validity that are more or less conditional to utility (i.e., coverage, and consistency with etiology and prognosis) and components of clinical utility in the narrow sense of the term (i.e., user acceptability and accuracy, communication, reliability, subtlety, and clinical decision making). Clinical utility is often considered the driving force behind the respective revisions of the DSM system, yet it has been difficult if not impossible to obtain reasonable levels of clinical utility within categorical classifications of personality disorders. This paper presents evidence that a dimensional diagnostic system will substantially improve clinical utility, especially with respect to coverage, reliability, subtlety, and clinical decision making. In addition, some evidence suggests that the purely dimensional models outperform the so-called hybrid models (i.e., dimensional profiling of categories) with respect to coverage, consistency with etiology, subtlety, and clinical decision making. Several research options that might inform future revisions, including the choice or development of a dimensional classification, are suggested.