Comments on the Diagnosis of the Schizophrenic Syndrome

Aksel Bertelsen1

The introduction of a non-aetiological criteria-based diagnostic classification in ICD-10 and DSM-III/IV has represented a major advantage in psychiatric research and clinical psychiatry. This applies particularly to the schizophrenic syndrome, which previously was diagnosed in widely different ways in various countries even within the frame of ICD-8 and ICD-9 [1]. The diagnostic approach based upon operationally defined criteria ensures a high reliability of the schizophrenic syndrome in schizophrenia, schizoaffective disorder, DSM-IV schizophreniform disorder and ICD-10 acute schizophrenia-like psychotic disorder. Reliability, however, does not guarantee validity, but all the same is an indispensable prerequisite for obtaining a diagnosis of useful validity. How does it help to have a definition of schizophrenia of high validity, if other psychiatrists are unable to reproduce the diagnosis because of lack of explicit criteria, which could be operationalized? Previously, ''autism'' or "schizophrenie-gefiihl" have been

1Aarhus Psychiatric Hospital, DK-8240 Risskov, Denmark suggested as nuclear phenomena for the schizophrenia diagnosis, but both have so far resisted attempts to be operationalized in order to be used as diagnostic criteria, probably because of the inherent subjective component on the part of the observer with poor inter-observer reliability.

The Schneider's first-rank symptoms have proved to be particularly useful because they are purely descriptive and operationalizable, and they are therefore applied in both the ICD-10 and DSM-III/IV criteria, although with different emphasis. Schneider claimed that the first-rank symptoms were highly characteristic for schizophrenia, but not pathognomonic, because they also appear in psychotic disorders with organic aetiology, which therefore has to be excluded. It has been stated that first-rank symptoms appear quite frequently in affective disorders [2]. This probably has been caused by inappropriate understanding of the proper definitions of these symptoms, which have to be assessed very carefully following the explicit description by Schneider to avoid false-positive assessments [3]. The first-rank symptoms of hallucinatory commenting and discussing voices thus have to be in the third person, assessed by two or three cited examples of their verbatim content. Subjective disorders of thoughts and control are not only delusions, but also and foremost experiences of thought insertion, withdrawal or broadcasting, or of foreign control of actions, feelings or will. But to avoid false-positive assessments, Schneider required explanatory delusions to accompany the experiences to ensure their presence [4]. The same applies to passivity or influence phenomena, which are combinations of somatic hallucinations and explanatory delusions, which both have to be present. This is, however, not made sufficiently explicit in the ICD-10 and DSM criteria for schizophrenia and the schizophrenia-related disorders, but has been taken into consideration in the Present State Examination included in the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) Version 2.1, for diagnostic assessment according to both ICD-10 and DSM-IV [5].

Unfortunately, the ICD-10 and DSM-IV criteria differ, particularly for schizoaffective disorders. ICD-10 and DSM-IV both require concurrent affective and schizophrenic syndromes. DSM-IV further requires at least 2 weeks with delusions and hallucinations in the absence of prominent mood symptoms. In contrast to ICD-10, DSM-IV allows schizophrenia-characteristic symptoms to appear during mood disorders. The ICD-10 definition of schizoaffective disorder, therefore, is much broader, including many cases of DSM-IV mood disorders with psychotic symptoms. The ''new'' diagnosis, ''schizoaffective disorder'', introduced with ICD-10 and DSM-III-R/IV, therefore, is in particular need of validation to see which of the concepts is the more valid. External validation by genetic research as the most promising has so far pointed to a strong genetic aetiological factor with morbid risk figures higher than for mood disorders or schizophrenia, but with no indication of a separate independent disorder. A combination of mood disorder and schizophrenia genes seems the most probable explanation, with secondary cases of mood disorder and to a lesser degree schizophrenia among the first-degree relatives, and only a minor risk of schizoaffective disorder [6].

For schizophrenia, the genetic aetiological factors are well demonstrated. That ''schizophrenia is a disorder of unknown aetiology'' is correct only in the sense that the aetiology and pathogenesis is not completely clarified and fully demonstrated. We do indeed know much about aetiology with dominating genetic factors in a multifactorial aetiological model, which also has been clearly demonstrated for DSM and ICD-10 schizophrenia [7]. Identification of one or more of the schizophrenia genes is, however, still awaiting the results from intensive research in molecular genetics. This would allow elucidation of the pathogenetic development of the schizophrenic syndrome, establishing schizophrenia as a truly nosological entity or, probably, entities, a group of schizophrenias as Bleuler suggested when he introduced the term.

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