Classification of anxiety and depressive disorders: problems and solutions.

The American Psychiatric Association and the World Health Organization have begun to revise their classifications of mental disorders. Four issues related to these revisions are discussed in this study: the structure of the classifications, the relationship between categories and dimensions, the sensitivity of categorical thresholds to definitions, and maximizing the utility and validity of the diagnostic process. There is now sufficient evidence to consider replacing the present groupings of disorders with an empirically based structure that reflects the actual similarities among disorders. For example, perhaps the present depression and anxiety disorders would be best grouped as internalizing disorders. Most mental disorders exist on a severity dimension. The reliability and validity of the classification might be improved if we accepted the dimensional nature of disorders while retaining the use of categorical diagnoses to enhance clinical utility. Definitions of the thresholds that define categories are very susceptible to detail. In International Classification of Diseases-11(ICD-11) and Diagnostic and Statistical Manual of Mental Disorders-V (DSM-V), disorders about which there is agreement should be identically defined, and disorders in which there is disagreement should be defined differently, so that research can identify which definition is more valid. The present diagnostic criteria are too complex to have acceptable clinical utility. We propose a reduced criterion set that can be remembered by clinicians and an enhanced criterion set for use with decision support tools.