Thomas A. Ban
Neuropsychopharmacology in Historical Perspective

Psychopharmacology and the Classification of Functional Psychoses


5. The KDK Budapest


       Instrumental for writing this text was the development of a set of diagnostic criteria for research (Kutatasi Diagnostikus Kriteriumok -  KDK in Hungarian) for “functional psychoses” in the early 1980s by a Hungarian team led by Bertalan Pethö, a professor of psychiatry at Semmelweis Medical University in Budapest.

       The KDK Budapest, published in 1984 in Hungarian (Pethö, Ban, Kelemen et al. 1984) is a “four-dimensional” classification that is rooted in cross-sectional psychopathology, with an extension of its boundaries beyond experiential phenomenology to behavior, performance and holistic (Gestalt) characteristics of the illness (Ban 1982; Conrad 1958; Pethö, Tolna and Tusnády 1979; Petrilowitsch 1969).

       The classification was presented as a “decision tree” with consideration of all four developmental stages of psychiatric illness.  In the KDK, first “exogenous” (“reactive”) psychoses are separated from “endogenous psychoses” on the basis of the relative importance of a precipitating event in activating the disease process. Subsequently, psychopathological syndromes are identified on the basis of an analysis of pathological forms of experiences with consideration of their content. The formal characteristics of the course of the disease, such as rhythmicity, periodicity, polarity, etc., are distinguished from the con­tents of the course, such as time spent in hospital, intensity of manifestations and duration of pharmacotherapy, etc. (Pethö 1984a). Finally, the outcome characteristics of the illness are utilized in the validation of diagnoses (Pethö 1977, 1984b).

       As indicated before, with employment of the KDK first “psychogenic psychoses” are separated from the “endogenous.”  Then, within the “psychogenic psychoses” “regressive,” “affective” and “paranoid psychogenic psychoses” are distinguished from   “delusional development” and within the “endogenous psychoses,” “schizo­phrenic” and “affective (phasic) psychoses” are distinguished from the “cycloid psychoses.”

       Subsequently, schizophrenic psychoses are divided into “nonsystematic” and “systematic schizophrenias” manifest in several “forms” and  ”sub-forms.” Moving further and further on the “decision tree,” within the  “nonsystematic schizophrenias” “affect-laden paraphrenia” is separated from “cataphasia”   and   “periodic   catatonia”; and  within the “systematic schizophrenias” the “catatonias” (para­kinetic, proskinetic, speech-prompt, speech inactive, manneristic and nega­tivistic) from the  “hebephrenias” (silly, eccentric, shallow and autistic) and the paraphrenias” (hypochondriacal, phonemic, incoherent, fantastic, confabulatory and expansive). Similarly, “cycloid psychoses” are divided into “anxiety-elation” (anxious or elated), “confusion” (excited or inhibited) and “motility psychoses”  (hyperkinetic or akinetic) affective psychoses. Finally,  the “affective (phasic) psychoses” are divided into “bipolar” and “unipolar psychoses” and within the “unipolar affective psychoses” “pure melancholia” and “pure mania” are  separated from the “pure depressions” (manifest in one of five forms: harried, hypochondriacal, self-torturing, sus­picious or non-participatory) and the “pure euphorias,”  manifest also  in one of five forms: unproductive, hypochondriacal, enthusiastic, confabulatory or non-participatory). 

       The KDK Budapest is more detailed and subtle than any other classification of “functional psychoses” used today in clinical practice and/or research. By adopting Karl Leonhard’s classification of “endogenous psychoses,” the KDK Budapest identifies biologically (pharmacologically) more homogenous populations than identified by currently used consensus-based classifications. 

       Supportive of the  contention than the psychiatric populations identified in Leonhard’s  (1957, 1979) classification, and consequently in the KDK Budapest, are biologically – pharmacologically more  homogenous than the populations identified in other classifications in psychiatry – are findings by Christian Astrup (Astrup 1959) and  Fish (1964) which indicate  that  therapeutic responsiveness to neuroleptics in patients diagnosed on the basis of Leonhard classification, classified on the basis of Leonhard’s system, was more predictable than in patients diagnosed by any other classification. With the employment of Leonhard's classification, Fish, in 1964, found that 117 out of 123 “nonsystematic schizophrenic” patients (95%) showed a favorable therapeutic response to neuroleptics, whereas only 289 out of 351 “systematic schizophrenic” patients (69%) showed a similar response (Fish 1964). Probably even more impressive was his findings that among “nonsyste­matic schizophrenic” patients a favorable therapeutic response was rated marked to moderate in 79% of the treatment responsive patients, whereas amongthe  “systematic schizophrenic” patients it was rated marked to moderate in only 23%. Fish also noted that among the “nonsystematic schizophrenic” patients, those with the diagnosis of “periodic catatonia” responded less favorably than patients with the diagnosis of “affect-laden paraphrenia” and “cataphasia,” and among the “systematic schizophrenic” patients those with “systematic catatonia” and hebephrenia” responded less favorably to neuroleptics than patients with “systematic paraphrenia.” This was to the extent that moderate or marked thera­peutic response was seen in as high as 40% of the patients belonging to one or another subtype of the systematic paraphrenias, whereas a similarly favor­able therapeutic response was seen only in 23% of the patients in one or another subtype of  “systematic hebephrenia” and in 0.9% of the patients with   one or another subtype of  “systematic catatonia.”

       The contention that employment of Leonhard's classification can identify biologically more homogenous and thereby more meaningful psychiatric populations than identified by other classifications is supported also by findings about the occurrence  of “tardive dyskinesia” (TD) in  a multinational survey of 768 chronic hospitalized schizophrenic patients (Ban, Guy and Wilson 1984a). In this survey the over­all prevalence rate of TD for the entire population was 11% when determined by clinical judgment and 13% when determined by the Research Diagnostic Criteria for Tardive Dyskinesia (Schooler and Kane 1982). However, by employing Leonhard's diagnostic system, prevalence rates were found to be significantly lower in the therapeutically more responsive “non­-systematic schizophrenic” group (4.3%) than in the therapeutically less responsive “systematic schizophrenic” group (13.3%). The “manneristic” subtype of the “systematic catatonias” attained a prevalence rate of 28% and the silly subtype of the “systematic hebephrenias” attained a prevalence rate of 53%. In the “expansive” and “confabulatory” subtypes of the “systematic paraphrenias,” TD was not encountered at all (Guy, Ban and Wilson 1985). Considering that there is no indication that patients with different types of schizophrenia, as classified by the ICD-9 or DSM-Ill, develop TD differentially to neuroleptics, the findings of differential occurrence  of TD in the different forms and sub-forms  of “schizophrenia” within Leonhard's classification favor the contention that diagnoses based on Leonhard's system provide for biologically more homogenous populations than diagnoses based on other systems of classifica­tion.

       In the KDK Budapest the term “psychosis” was retained for the various diagnoses in order to indicate that its diagnoses represent different forms and sub-forms of disease  and not “psychic abnormalities,” i.e., statis­tical deviations from the social norm (normal) with which they are “united by a series of imperceptible transitions” (Schneider 1950, 1959).


Diagnostic Assessment Scale


       The KDK Budapest was translated into English in Nashville in the early 1980s with the title “Diagnostic Criteria for Research (DCR) Budapest—Nashville.” To assist its use by those unfamiliar with the terminology used in its decision tree, the Diagnostic Assessment Scale referred to as DAS presented here, was developed.  

       The DAS is based on 396 items presented in 12 tables with each table representing one step in the differential diagnostic process.                            

       In completing DAS the following time frames are considered:

1.Presence of psychosis (one-dimensional diagnosis) can be usually determined by a single examination. It should be possible definitely within eight days.

2.At least two weeks of continuous observation with repeated - at least three careful assessments - are required to clarify the nature of the psychosis.

3.Course of disease refers to periods with a duration of at least five years. Formal characteristics of the course, such as rhythmicity-periodicity, polarity and deterioration are distinguished from the content of the course, such as time spent in hospital, nature of  therapies.

4.The evaluation of outcome, e.g., after five years, is always done in terms of the presence of psychopathological symptoms and impairment of social adjournment.


       Thus, for a final diagnosis with the employment of the DAS, cross-sectional findings (diag­nostic impressions) are supplemented with information on the course of the disease (provisional diagnosis) and outcome data (final diagnosis).

       Despite of all its complexities, inter-rater agreement with the DAS between two raters was  92 % in a small pilot study. For the most distal diagnostic endpoints of the decision tree (subtypes) agreement was only 77% but for the three major groups of “systematic schizophrenia” (hebephrenia, catatonia and paraphrenia) the agreement was 100%.

       In addition to reliability, the pilot study also explored the relationship between DAS and DSM-III diagnoses. For this part of the study, 96 randomly selected patients from the acute and chronic services of a mental hospital  (Central State Hospital in Nashville)  were subtyped by DAS criteria and the resulting diagnoses were cross-tabulated with DSM-III diagnoses. Although overall agreement for all diagnoses was only 45% (Cramer's statistics 'I' = 0.45), it was noted that in patients with systematic schizophrenia on the DAS, 92%  were diagnosed as schizophrenic by the DSM-III. Agreement was considerably lower (57%) between DAS diagnoses of nonsystematic schizophrenia and DSM-III diagnoses of schizophrenic disorders. However, the agreement for schizophrenic diagnoses between DAS and DSM-III diagnoses would have been 100% if schizoaffective disorders had been excluded from schizophrenic disorders in the DSM-III.

       Employing the DAS in the assessment of a large-number of patients has brought to attention that the diagnosis  concept of  delusional  development might provide a transition between the psychogenic (exogenous) and autochthonous (endogenous) psychoses.



Astrup C. The effects of ataraxic drugs on schizophrenic subgroups related to experimental  findings. Acta Psychiatr Scand Suppl, 1959;34:388-93. 

Ban TA. Chronic schizophrenias: A guide to Leonhard's classification. Compr Psychiatry, 1982;23:155-70.  

Ban TA, Guy W, Wilson WH. Description and distribution of the subtypes of chronic schizophrenia based on Leonhard's classification. Psychiatr Dev, l984a;3:179-99. 

Conrad K. Die beginnende Schizophrenie: Versuch einer Gestaltanalyse des Wahns. Stuttgart: Thieme; 1958. 

Fish FJ. A guide to the Leonhard classification of chronic schizophrenia. Psychiatr Q, l964;38:438-50. 

Guy W,  Ban TA, Wilson WH.         An  international survey of tardive dyskinesia. Prog Neuropsychopharmacol Biol Psychiatry, 1985;9(4):401-5. 

Leonhard K. Aufteilung der endogenen Psychosen.            Berlin: Akademie-Verlag; 1957. 

Leonhard K. The Classification of Endogenous Psychoses. 5th Edition. Edited by Eli Robins; Translated from the German by Russell Berman. New York, London, Sydnet: Irvington Publishers; 1979. 

Pethö B. Dimensional assessment of the course of psychiatric illness. Psychopathology, 1984a;17:110-16.  

Pethö B. Hour-glass model of the psychiatric illness. Schizophrc Bull, 1984b;10:509-19. 

Pethö B. Die Struktur der residualen Dimension. Einige Ehrfahrungen einer  funfjahrigen,   kontrollierten  Follow-up  Studie  schizophrener Kranken. Psychiat Clin, 1977;10:173-85. 

Pethö B, Ban T, Kelemen A, Ungvari  G,  Karczag I, Bitter I, Tolna J. KDK Budapest. Kutatasi   Diagnosztikai Kriteriumok functionalis psychosisok korismezesehez. Ideggyogyaszati Szemle, 1984;37:102-31. 

Pethö B, Tolna J, Tusnády G. Multi-trait-multi-method assessment of predictive variables of outcome in schizophrenia spectrum disorders. A nosological evaluation. J Psychiatr Res, 1979;15:163-74. 

Petrilowitsch N. Die Schizophrenien in structurpsychiatrischer Sicht. Psychiat Clin, 1969;2:289-306. 

Schneider K. Klinische Psychopathologie. Stuttgart: Thiemet; 1950. 

Schneider K. Clinical Psychopathology. Translated from 3rd edition by MW Hamilton and EW Anderson. New York: Grune and Stratton; 1959. 

Schooler N, Kane JM. Research diagnoses for tardive dyskinesia (RD - TD). Arch Gen Psychiatry, 1982;39:486-7.


May 6, 2021