The DSM-5 approach to psychotic disorders: Is it possible to overcome the ‘inherent conservative bias’?

Abstract

It is hard not to perceive, going through this series of papers, some sense of dissatisfaction by the members themselves of the DSM-5 Work Group on Psychotic Disorders about the outcome of their effort. There is an explicit acknowledgment in the papers that the current diagnostic approach to schizophrenia and other psychotic disorders is not only far from optimal, but may even contribute to the lack of progress of research (Heckers et al., 2013). However, both the Work Group and the DSM-5 Task Force felt that no better alternatives were available (Heckers et al., 2013; Tandon et al., 2013). So, there has been an “inherent conservative bias” (Heckers et al., 2013) in the DSM-5 approach to the diagnosis and classification of psychotic disorders. The question addressed in this commentary is whether it was possible (or it is possible, since the DSM-5 is reported to be “a living document” to be updated regularly) to do something more to overcome that bias. A first expected development in the DSM-5 chapter on schizophrenia and psychotic disorders was the introduction of a dimensional approach, complementing the categorical one, aimed to encourage a more detailed clinical characterization of the individual patient and to guide research into the pathophysiological correlates of the various components of psychotic syndromes. However, contrary to the Work Group's advice (Barch et al., 2013), the dimensional scale only appears in the final Section III of the manual. The reported rationale is the DSM-5 Task Force's concern that “clinicians do not yet know how to use these dimensions and that more experience with them is needed before they are placed in the primary text” (Barch et al., 2013, p. 11). However, the inclusion of these dimensions in an appendix of the manual does not really represent a new development. “Alternative dimensional descriptors for schizophrenia” were already included in the Appendix B of the DSM-IV (American Psychiatric Association, 1994, p. 710–711), and “a system for applying these dimensions in research and clinical studies”, with a four-point scale ranging from “absent” to “severe”, was already proposed there. However, that dimensional system has been practically ignored in the past 20 years by both clinicians and researchers. Interestingly, it represents the only item of the DSM-IV Appendix B which has transited to the DSM-5 Section III, rather than being either moved to the DSM-5 main text or deleted. This precedent is certainly not encouraging. Placing a dimensional system in an appendix of the diagnostic manual may not be the most effectiveway to encourage its use, especially if the structure of the system