Prolegomenon to the Clinical Prerequisite; Psychopharmacology and the Classification of Mental Disorders
(Volume 1)

Conceptual Development of Current Psychiatric Nosology

Thomas A. Ban and Antonio Torrez Ruiz

Prerequisites of Psychiatric Nosology

It was in the Medical Dictionary of Robert James, published in London in 1743, that the term "nosology" appeared for the first time. Twenty-five years later, in 1768, the term reappeared in the title of Boissier de Sauvages treatise, Nosologia Methodica, the first acknowledged classification of mental disorders. The influence of Nosologia has been so great and long-lasting, that even today we use the term "nosology" in a sense of a "methodology" in the "diagnosis" and "classification" of mental disorders (Lehmann, 1971).

Naturally Occurring Categories of Psychiatric Disorder

The origin of the first essential prerequisite of a "psychiatric nosology" -- that naturally occurring categories of mental illness exist -- was in the work of Boissier de Sauvages (1768). As a "botanist" and a recognized "specialist" in "mental illness" (Cullen, 1810), he was especially well prepared for adopting the two basic rules of Linne (1735) -- for classifying flowering plants and ferns -- to the classification of psychiatric disorders. Accordingly, he maintained that "psychiatric nosology" should consist of "categorical diagnoses" which are based on criteria, or special characteristics, which "allow the attribution of each patient to one and only one class," and should represent a "natural classification" of the disease categories thereby identified.

Boissier de Sauvages (1768) was "an outspoken advocate of symptomatological nosology." He firmly believed that "a disease should be defined by the enumeration of the symptoms which suffice to recognize it and to distinguish it from others" (Rosenzweig, 1982). Because of his strong influence, the first important "nosologies" -- Pinel's (1801) and Esquirol's (1838) -- were "descriptive classifications which defined empirically isolated syndromic classes" (Pichot, 1986).

Dynamic Totality of Psychiatric Disease

The origin of the second "essential prerequisite" of a "psychiatric nosology"-- that naturally occurring categories of mental illness represent a "dynamic totality" -- was in Falret's (1864) notion that "a natural form of psychiatric illness implies a well-defined predictable course" and vice versa "a well-defined predictable course presupposes the existence of a natural species of disease with a specific pattern of development." By focusing attention on the evolution of symptomatic expressions, i.e., on the natural history of psychiatric illness, Falret (1864) has opened the path for "nosologies" which are based on an increasing number of developmental stages of psychiatric disorders. An important role in this development was played by Kahlbaum (1874), who put forward the task "to use clinical methods in the study of the developmental picture of psychiatric illness." He maintained that for diagnostic purposes "the whole course of illness must be taken into account."

The new conceptual framework was applied by Kahlbaum (1874) to the description of "catatonia." Subsequently, it was adopted by Kraepelin (1896) for the description of the whole field of mental illness. Because of this, it was Kraepelin (1896) whose system of diagnostic classification combined for the first time "a careful description of symptoms and syndromes with their course and outcome" (Lehmann, 1971). Kraepelin (1896) believed that the "clinical pictures of disease with similar causes, a similar psychological form and similar cerebral pathology, are genuine-natural disease entities." However, his major contribution to psychiatric research was in the shift of emphasis from the "course of illness" -- which remained the focal point for Kahlbaum (1874) -- to the "outcome picture." His rationale for the shift of emphasis was in the supposition "that knowledge of the psychological structure of the outcome" would allow the detection of "the basic psychological forms of the disease process even in the finest of indications at the very beginning" of the disorder (Jaspers, 1962).

Determining Structure of Psychiatric Disease.

The origin of the third "essential prerequisite" of a "psychiatric nosology" -- that each psychiatric disorder is defined by a specific "determining structure" -- is in the work of Jaspers (1962), who was the first to note that psychiatric "diagnosis can only be made from the total picture when one knows 'a priori' of a definite illness that can be diagnosed."

The term "determining structure" was put forward in the Prolegomenon to the Clinical Prerequisite by Thomas A Ban (1987). It refers to the form of the mental illness, i.e., the "pattern" that is predetermined by the illness, which cannot be reduced to the sum of information from the subsequent developmental stages (dynamic totality) of the disorder.