Subthreshold disorders in psychiatry: clinical reality, methodological artifact, and the double-threshold problem

The introduction of modern operationalized classification systems for mental disorders has led to the issue of subthreshold disorders. Definitions for illness do not at the same time define health, e.g., in the sense of the World Health Organization (WHO) definition from 1947. The threshold not only to define disorders but also to define health is open to discussion. So-called subthreshold disorders require the definition of 2 thresholds. Empirical research has suggested that these "between-threshold disorders" are associated with increased disability and many other negative consequences. Part of the problem with subthreshold disorders is methodological in nature. Psychopathology and the Gestalt characteristic of psychopathological signs are ignored, and categorical instead of dimensional concepts are used. Thus, the distinction between syndromes and disorders, as well as the hierarchical structure of disorders, is not taken into account, and statistical problems with the prognostic power, which is dependent on the epidemiological distribution, are not solved. Variations in threshold definitions have important consequences for the individual and for society, be it because of the negative effects of "diagnostic labeling" or because of the costs to the health care system. Treatment options are presently rather insufficient, although modern sequential treatment algorithms and newer treatments (e.g., selective serotonin reuptake inhibitors [SSRIs] and Saint-John's-wort) promise interesting perspectives. Also in this context, self-help should become an important area of medical treatment research.