The individual disorder definitions that constitute the operationalized sets of diagnostic criteria provide the core of DSM—5 for clinical and research purposes. These criteria have been subjected to scientific review, albeit to varying degrees, and many disorders have un- dergone field testing for interrater reliability. In contrast, the classification of disorders (the way in which disorders are grouped, which provides a high—level organization for the man- ual) has not generally been thought of as scientifically significant, despite the fact that judg- ments had to be made when disorders were initially divided into chapters for DSM-III.
DSM is a medical classification of disorders and as such serves as a historically deter- mined cognitive schema imposed on clinical and scientific information to increase its com- prehensibility and utility. Not surprisingly, as the foundational science that ultimately led to DSM-III has approached a half—century in age, challenges have begun to emerge for cli- nicians and scientists alike that are inherent in the DSM structure rather than in the de- scription of any single disorder. These challenges include high rates of comorbidity within and across DSM chapters, an excessive use of and need to rely on "not otherwise specified” (NOS) criteria, and a growing inability to integrate DSM disorders with the results of ge— netic studies and other scientific findings.
As the APA and the WHO began to plan their respective revisions of the DSM and the
International Classification of Disorders (ICD), both considered the possibility of improving clinical utility (e.g., by helping to explain apparent comorbidity) and facilitating scientific investigation by rethinking the organizational structures of both publications in a linear system designated by alphanumeric codes that sequence chapters according to some ra- tional and relational structure. It was critical to both the DSM-S Task Force and the WHO
International Advisory Group on the revision of the ICD—10 Section on Mental and Behav- ioral Disorders that the revisions to the organization enhance clinical utility and remain within the bounds of well-replicated scientific information. Although the need for reform seemed apparent, it was important to respect the state of the science as well as the chal- lenge that overly rapid change would pose for the clinical and research communities. In that spirit, revision of the organization was approached as a conservative, evolutionary di- agnostic reform that would be guided by emerging scientific evidence on the relationships between disorder groups. By reordering and regrouping the existing disorders, the re- vised structure is meant to stimulate new clinical perspectives and to encourage research- ers to identify the psychological and physiological cross-cutting factors that are not bound by strict categorical designations.
The use of DSM criteria has the clear virtue of creating a common language for com- munication between clinicians about the diagnosis of disorders. The official criteria and disorders that were determined to have accepted clinical applicability are located in Sec- tion II of the manual. However, it should be noted that these diagnostic criteria and their relationships within the classification are based on current research and may need to be modified as new evidence' is gathered by future research both within and across the do- mains of proposed disorders. “Conditions for Further Study,” described 1n Section III, are those for which we determined that the scientific evidence 15 not yet available to support widespread clinical use. These diagnostic criteria are included to highlight the evolution and direction of scientific advances in these areas to stimulate further research.
With any ongoing review process, especially one of this complexity, different viewpoints emerge, and an effort was made to consider various viewpoints and, when warranted, ac- commodate them. For example, personality disorders are included in both Sections II and
III. Section II represents an update of the text associated with the same criteria found in
DSM-IV-TR, whereas Section 111 includes the proposed research model for personality dis- order diagnosis and conceptualization developed by the DSM-S Personality and Personality
Disorders Work Group. As this field evolves, it is hoped that both versions will serve clin- ical practice and research initiatives.