Approaches to psychiatric nosology: A viewpoint.

Psychiatric nosology is required for communication among clinicians and researchers, understanding etiology, testing treatment efficacy, knowing the prevalence of the problems and disorders, healthcare planning, organizing the services, and reimbursement purposes. Many approaches have been used for psychiatric nosology, including categorical, dimensional, hybrid, and etiological. The categorical approach considers illness as being either present or absent, and similarity with prototypical description of a disorder is taken as a marker for the disorder. The dimensional approach regards that symptoms of disorder exist on a continuum from normal to severely ill. The hybrid approach combines categorical and dimensional approaches, with categorical diagnosis for broad diagnostic group and dimensional indicator for severity. The etiological approach tends to find "reason" for the set of symptoms, which could be biological, psychological, or social. In this article, certain critical issues about the different nosological approaches are discussed. Hybrid approach currently seems to be the most preferred for widespread usage. In conclusion, psychiatric nosology needs to evolve through epistemic iteration leading to successive changes and devising a more refined and useful system with time.