Diagnostic and Statistical Manual of Mental Disorders(DSM)

Epistemological Assumptions and Definition of

The Medical Model and Categorical Approach

Early in the evolution of the DSM, its creators attempted to establish a diagnostic system that was compatible with a broader worldwide medical taxonomy—that is, the International Classification of Diseases, Injuries, and Causes of Death (ICD) developed by the World Health Organization (WHO). Hence, the DSM adopts a medical model of diagnosis for which mental disorders, regardless of whether their etiology is biological or psychological, are viewed as “mental illnesses” requiring treatment. Furthermore, implicit in this model is the assumption that mental disorders comprise behavioral and psychological symptoms that form a distinct and definable pattern or “syndrome.” Thus, the creators of the DSM made a conscious choice to adopt a categorical taxonomy of mental illnesses. It is important to note, however, that the DSM makes no assumption that all mental disorders are discreet entities with absolute boundaries. Rather, it adopts a prototype model with several accommodations for the “fuzzier” diagnostic situations and for within-disorder heterogeneity. These accommodations include the use of severity specifiers and subtypes, general categories for clinically significant conditions that do not meet the specifications for more specific categories (but nonetheless require clinical attention), and polythetic criteria sets whereby diagnoses are made based on a proportion of endorsed criteria out of a larger criteria set. The DSM has also made special efforts to increase cultural awareness and sensitivity in diagnosis by including descriptions of cultural variations in manifestations of DSM disorders, an appendix of known culture-bound systems that are not included in the DSM nomenclature, and a guide for cultural formulation.

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