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Work is currently underway on the fifth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM). Each new version of the manual reflects, in part, the progress in the understanding of psychopathology that has been accomplished since the previous version. This special section gathers summaries of several relevant advances of particular relevance for the Diagnostic and Statistical Manual of Mental Disorders revision process and, more generally, for any effort to describe psychopathology in valid and useful ways. Recent advances in the description of psychopathology have been dramatic, and there is an emerging consensus that fundamental changes to the diagnostic process are necessary to capture the validity and the utility of the description that is currently available in the field. The articles in this special section play 2 roles: They describe the fundamental changes that are necessary, and they provide a stepping stone for the next wave of advances in psychological assessment research.
Advances in understanding psychopathology and advances in describing it each contribute to the other as part of an ongoing, reciprocal process (Smith & Combs, in press; Strauss & Smith, 2009). Every improvement in understanding the nature and etiology of a given form of dysfunction improves the ability of investigators to describe it more precisely. And each improvement in the validity of description facilitates stronger and more valid research, thus contributing to subsequent advances in understanding. Each new version of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM) reflects, in part, the progress in understanding psychopathology that has taken place since the previous version, just as each new version also plays a role in shaping the next generation of psychopathology research questions.
The collection of summaries of recent advances in understanding and description in this special section reflects important shifts with regard to these issues and indicates that important progress has been made on both fronts. This progress shapes current scientific understanding of the nature of psychopathology and provides the framework for the next generation of clinical research questions. The developers of the fifth edition of the DSM (DSM–V) have the opportunity to take advantage of this progress and to produce a classification system that captures the improved validity and utility of description that is now available in the literature. To the degree that they do so, the DSM–V will continue to play its traditional role in shaping future research questions. Alternatively, failure to do so would risk making the DSM less relevant to scientific progress and both less valid and less useful than it could be.
Two articles in the special section reflect the emerging consensus that psychopathology is better described along continua than described with discrete categories. Widiger, Livesley, and Clark (2009) reported that a consensus, integrated dimensional system for describing personality disorders now exists. Prior to publication of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM–IV; American Psychiatric Association, 1994) researchers from different orientations had not yet converged on a personality disorder descriptive system; thus, despite the promise of dimensional description, a dimensional system could not be adopted (Frances, First, & Pincus, 1995). That has changed. Today, researchers from a variety of perspectives support a four-dimensional, continua-based system for describing personality dysfunction. Widiger and colleagues (2009) discussed this advance and reviewed the advantages of dimensional description, which include an end to unnecessary comorbidity and improved utility for clinicians. Brown and Barlow (2009) provided a dimensional model for describing anxiety and mood disorders. Among the advantages of their proposal are, again, a resolution of the comorbidity problem and a direct relationship between assessment and currently supported transdiagnostic treatment protocols. The focus in both of these articles on basic dimensions of dysfunction promises an escape from what now appears to be the excessive splitting of dysfunction into multiple, similar disorders that appear to be comorbid and that require similar treatments.
Nothing about description along dimensions precludes the development of cutting scores when specific, dichotomous decisions are necessary. As Kamphuis and Noordof (2009) noted, it is a straightforward matter to develop cutting scores from interval scale data, and doing so when necessary facilitates decision making without costing one all of the information available from dimensional assessment. A second advantage to beginning with dimensional description was demonstrated by Cooper and Balsis (2009). Once one measures dysfunction along a continuum, one can determine that certain symptoms tend to be associated with mild levels of dysfunction and that others tend to be associated with severe dysfunction. Cooper and Balsis (2009) showed that individuals with a nondiagnosable, small number of severe symptoms can have more pathology than do individuals who are positively diagnosed because they have more symptoms, when the symptoms endorsed by this latter group are associated with mild dysfunction.
One crucial advantage of describing psychopathology along dimensions of functioning is that it offers an alternative to the classic, syndromal approach to description. As noted in the special section, leaders of the DSM system have observed that the concept of syndromes has not borne fruit, thus “undermining the hypothesis that the syndromes represent distinct etiologies” (Kupfer, First, & Regier, 2002, p. xviii; two of these authors are Chair and Vice Chair of DSM–V). Syndromes are defined in terms of a set of related symptoms, and the same symptoms contribute to multiple disorders (are part of multiple syndromes). If different syndromes really did reflect constellations of symptoms with different etiologies, this complication may have been necessary. But after many years of systematic investigation, there is no evidence that they do. One of the common themes in the articles in this special section is that the syndromal approach may need to be jettisoned due to its lack of validity.
To discard the syndromal approach may be to improve the validity and utility of the diagnostic system. Patients can be described along dimensions of functioning. As Smith, McCarthy, and Zapolski (2009) noted, use of homogeneous dimensions of functioning improves the clarity of clinical description and facilitates more rapid scientific advances. The current practice of using a single score or a single diagnosis that can be based on different behaviors or psychological experiences for different individuals results in diagnoses that lack clear meaning and that may lack utility with respect to treatment planning.
In addition to new evidence cited in several of the articles concerning the utility of description by homogeneous dimensions, recent years have seen an increase in the study of the utility of diagnosis as separate from the validity of diagnosis. Mullins-Sweatt and Widiger (2009) presented an important overview of utility research. They noted that utility has not often been studied in the DSM process, and they argued persuasively that doing so is of crucial importance for the clinical applications of the diagnostic manual. It is striking to realize that the utility of diagnoses has actually received little empirical scrutiny; the utility of the dichotomous classification system has been more presumed than demonstrated.
Ro and Clark (2009) examined an issue of fundamental importance to both utility and validity, which is the valid assessment of psychosocial functioning separate from assessment of the specific symptoms used to define pathological constructs. It is of course the case that functional impairment is necessary to infer the presence of psychopathology: Mental disorders are necessarily defined in terms of the disadvantages that they convey to the individual. But at the same time, it is important to develop an assessment system that does not confound the assessment of symptoms with the assessment of the impact of those symptoms on individuals' daily functioning. Ro and Clark (2009) addressed this issue and point the way toward an empirical determination of the appropriate dimensions of functioning to be considered.
These times are exciting ones to be studying psychopathology, as advances on numerous fronts transform our understanding of dysfunction, along with our ability to describe it. The articles in this special section offer an interesting, important sample of these advances.
Portions of this work were supported by National Institutes of Health, in the form of National Institute on Alcohol Abuse and Alcoholism Grant RO1 AA 016166 to Gregory T. Smith and National Institute of Mental Health Grant RO1 MH077840 to Thomas F. Oltmanns.
Gregory T. Smith, Department of Psychology, University of Kentucky.
Thomas F. Oltmanns, Department of Psychology, Washington University in St. Louis.