Spectrum and nosology: implications for DSM-V

The authors attempt to show similarities and differences between a spectrum and the DSM-IV perspective in how psychopathology is best represented to clinicians and clinical researchers. Subthreshold symptoms are given little or no attention in DSM; noncriterion symptoms are given none at all. Not otherwise specified disorders may be a widely used category in DSM-IV, but in a spectrum diagnosis there is no similar designation, because use of the whole spectrum of symptoms is possible. Although a DSM-IV categorical disorder may not be the best representation of psychopathology, it is clearly defined and is efficient for the purposes of communication and labeling. Both systems of nosology are essentially atheoretical; comorbidity exists in both, although to a lesser degree in some spectrum models. Data are summarized that clearly demonstrate the need for designers of DSM-V to create a nosology that is, at least in part, dimensional.