Thomas A. Ban
Neuropsychopharmacology in Historical Perspective

Psychopharmacology and the Classification of Functional Psychoses

2. Introduction

       Recent progress in epidemiological and biological research in mental disorders has led to a revival of interest in psychiatric diagnosis and classification.  

       The new trend has received an impetus from the notion that operationally defined diagnostic criteria might be prerequisites for a valid comparison of epidemiological data from different language areas; for the identification of biological markers of disease; and for the demonstration of the effectiveness of new psychotropic drugs. In addition to their importance for psychiatric research, diagnoses in psychiatry provide the "necessary end points" (targets) for choosing suitable treatment to provide the necessary "care and counselling" to "the psychiatrically ill" (Helmchen 1980).

Multi-Axial Classifications

       To improve pharmacological homogeneity and thereby predictive validity of psychiatric diagnoses in treatment, several multi-axial classifications have been proposed.

       A rationale for separating "etiology" from "symptomatology" was offered by Essen-Möller (1961). He contended that by assessing patients on  two different, independent "axes,” a number of combinations of syndromes would emerge which might not correspond to traditional (syndrome or phenotype-based) psychiatric  diagnoses  and  thereby  invalidate  some  of  the  old diagnostic  hypotheses. By designing a model for a bi-axial system Essen-Möller (1961) opened a new path leading to the development of multi-axial systems of diagnostic classifications in psychiatry.

       The first models of multi-axial systems of diagnostic classifications in psychiatry were developed independently by Ottosson and Perris (1973) and Helmchen (1975). They entailed four and five axes, respectively. The four axes of Ottosson and Perris (1973) are “symptomatology,” "severity," "etio­logy" and "course." The five axes of Helmchen (1975) are “symptomatology,” “time,” “etiology,” “intensity” and “certainty.”   

       Other important multi-axial classifications are those of Wing, Bramley, Hailey and Wing  (1968) and Strauss (1975). The four axes of Wing, Bramley, Hailey and Wing (1968) are “psychiatric condition,” “underlying cause or precipitating factor,” “mental sub-normality” and “additional physical illness or handicap.” The five axes of Strauss (1975) are “symptoms,” “previous duration,” “course of symptoms associated with diagnostic factors,” “personal relationships” and “work function.”

       A significant, recent contribution to multi-axial psychiatric diagnosis is the Third Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) of the Ameri­can Psychiatric Association  (APA 1980). By its operationally defined diagnostic criteria and multi-axial system of evaluation, DSM-III represents an important step towards a “scientific” approach to psychiatric diagnosis.

       Important contributions to the development of operationalized diag­nostic criteria are the St.  Louis Criteria of Feighner, Robins, Guze et  al. (1972); the Present State Examination of  Wing,  Cooper  and  Sartorius  (1974); the Research Diagnostic Criteria (RDC) of Spitzer, Endicott  and  Robins (1978a,b); Taylor and Abrams Criteria (Taylor and Abrams 1978; Taylor, Redfield and Abrams 1981); and the Vienna Research Criteria of Berner and Katschnig (1983).

Empirical, Experimental or Nosology Derived Diagnoses

       Findings which have accumulated during the past decades strongly suggest that diagnoses in psychiatry, regardless whether phenotype-based or nosology derived, are only in part homogenous entities. This is reflected in the differential responsiveness within the same diagnostic category to the same psychotropic drug given in the same dose, and in the considerable variation of neurophysiological and biochemical measures within the same diagnostic cat

       In the absence of well-identified etiology in most psychiatric disease, there were three are three approaches employed during the 1950s, ‘60s and ‘70s with the hope to derive to biologically (pharmacologically) more homogenous patient populations: the “empirical,” the “experimental” and the “nosological.”

       The “empirical” approach is based on the development of an assessment instrument, e.g., rating scale, that is constructed in a manner to include as many as possible known manifestations of a psychiatric disease, e.g., depression. It is assumed that by administering such a scale to large, seemingly homogenous populations clinically with the employment of  statistical procedures, such as factor analysis, cluster analysis, multiple discriminant function analysis in the treatment of collected data, meaningful subtypes or diagnoses within a group of disorders will be obtained.

       An alternative to the empirical approach is the “experimental approach.” It is based on biological measures, e.g., neurophysiological, bio­chemical, neuroendocrine. While it is hoped that some of these measures (biological markers) will bring about a more meaningful classification of clinical psychopathology, the fact remains that the meaningfulness of biological  markers is limited by the extent that they can be linked to a clinically identifiable biologically homogenous diagnostic group.

       The prototype of the third or “nosology derived” diagnoses is Kraepelin's (1896) classification that was presented for the first time in the 5^th edition of his textbook. Kraepelin's classification is based on three successive stages (referred to here as dimensions) of psy­chiatric disease. In the first four-editions of his text, Kraepelin used a syndrome-oriented approach to the classification of mental illness. Beginning with the fifth edition he adopted the medical concept of psychiatric disease and shifted emphasis from the "pathological picture" to the “criterion of progress" (Pichot 1983). According to Kraepelin the necessity "for the shift in emphasis to the criterion of progress was  brought  about by practical  needs": 1) by  the "limitations of  grouping on the basis of pathological pictures (Krankheitsbilder); and 2) by the recognition of the importance of  criteria "which derive from the developmental stages, the course  and   the   outcome  of  individual  disorders."

       Kraepelin’s shift of emphasis from the cross-sectional picture to the course of  illness had   its origin in Kahlbaum's (1874) formulation of the notion of “nosological entity.” It was based essentially on Falret's (1864) contention that for a better understanding one has to learn about "the progression and the various stages of  the natural form of mental disorders." For Falret, a "natural form" of a disease "implies a well-defined predictable course," which in turn "presupposes the existence of a natural form of disease with a specific pattern of development."

       Today, in the 1980s, an alternative to Kraepelin’s three-dimensional (onset, course and outcome) nosology is Karl Leonhard’s four dimensional nosology in which Kraepelin’s three dimensions are supplemented with “polarity,” a fourth “dimension. It was first presented in Karl  Leonhard’s (1957, 1979)  text, Classification of Endogenous Psychoses, published in 1957.

From One to Four Dimensional Classifications

       "Axes" and "dimensions" in reference to classifications are entirely different concepts since  in “axes” emphasis is on the independence of the components whereas in dimensions the emphasis is on relationships among the components.

       A one-dimensional classification in this presentation refers to a classification that is based entirely on “psychopathology,” whereas a two-dimensional is based on psychopathology with consideration of the form of onset of the illness;  a three dimensional is based on psychopathology with consideration of onset, course and outcome; and a four dimensional on psychopathology with consideration of onset, course, outcome and polarity. 

       By considering an increasing number of “dimensions,” the pharmacologically heterogenous   population of patients with mental illness could be separated into increasingly more homogenous groups clinically which were increasingly distinct from each other. Thus, by employing a two-dimensional approach, the one-dimensional con­cept of unitary psychosis, once referred to as the “vesania” (Neumann 1859; Griesinger 1845, 1867, 1876), could be separated into two psychoses, i.e., “exogenous” and “endogenous.” Introduction of the third dimension opened the possibility of separating patients within the population of  “exogenous”  psychosis   into “organic” (including “symptomatic psychosis” and “psychosis associated with coarse brain disease”) and “psychogenic” (also referred to as “reactive” psychoses); and to separate patients within the population of endogenous psychoses into “schizophrenic” (dementia praecox) and “affective” (manic depressive) psychoses. As “psychogenic: and “endogenous” psychoses are considered to be sui generis psychiatric illnesses, they are commonly referred to as “functional psychoses” to separate them from the non-specific psychiatric disorders associated with neurological or other systemic diseases and from developmental, inborn or learned anomalies, such as mental retardation and psychopathic personalities (Schneider 1925).

       Introduction of the fourth dimension made it possible to separate patients within both the “schizo­phrenic” and the “affective” psychoses into two major diagnostic groups, i.e., “nonsystematic” (also referred to as “unsystematic”) and “systematic” schizophrenias, and “unipolar” and “bipolar” affective” psychoses. The four-dimensional model of psychiatric diagnosis focused attention also on “delusional psychosis,” a population between the “reactive” and “endogenous” psychoses, and on “cycloid” psychosis, a population between the “affective” and “schizophrenic” psychoses. It also brought to attention numerous subtypes within each group of diagnoses.

       Taking into consideration the entire disease from beginning to end is a prerequisite for a comprehensive picture that provides for a better understanding of the nature of psychiatric illness. In keeping with this is Kahlbaum’s (1874) notion that “only an inclusive and general use of the clinical method can advance psychiatry and increase understanding about the pathological process involved in mental illness.”

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April 15, 2021