Phenomenology of Schizophrenia and the Representativeness of Modern Diagnostic Criteria

Abstract

Importance: This article aims to determine the degree to which modern operationalized diagnostic criteria for schizophrenia reflect the main clinical features of the disorder as described historically by diagnostic experts.

Observations: Amazon.com, the National Library of Medicine, and Forgottenbooks.com were searched for articles written or translated into English from 1900 to 1960. Clinical descriptions of schizophrenia or dementia praecox appearing in 16 textbooks or review articles published between 1899 and 1956 were reviewed and compared with the criteria for schizophrenia from 6 modern US operationalized diagnostic systems. Twenty prominent symptoms and signs were reported by 5 or more authors. A strong association was seen between the frequency with which the symptoms/signs were reported and the likelihood of their presence in modern diagnostic systems. Of these 20 symptoms/signs, 3 (thought disorder, delusions, and hallucinations) were included in all diagnostic systems and were among the 4 most frequently reported. Three symptoms/signs were added then kept in subsequent criteria: emotional blunting, changes in volition, and changes in social life. Three symptoms/signs were added but then dropped: bizarre delusions, passivity symptoms, and mood incongruity. Eleven symptoms/signs were never included in any diagnostic system. Compared with historical authors, modern criteria favored symptoms over signs. Odd movements and postures, noted by 16 of 18 historical authors, were absent from all modern criteria. DSM-5 criteria contain 6 of the 20 historically noted symptoms/signs.

Conclusions and relevance: Although modern operationalized criteria for schizophrenia reflect symptoms and signs commonly reported by historical experts, many clinical features emphasized by these experts are absent from modern criteria. This is not necessarily problematic as diagnostic criteria are meant to index rather than thoroughly describe syndromes. However, the lack of correspondence in schizophrenia between historically important symptoms/signs and current diagnostic systems highlights the limitations of clinical evaluations and research studies that restrict the diagnostic assessments to current diagnostic criteria. We should not confuse our DSM diagnostic criteria with the disorders that they were designed to index.