THE DIAGNOSIS OF SCHIZOPHRENIA - CHANGES INFLUENCED BY OPERATIONALIZED DIAGNOSTIC SYSTEMS AND EFFECTS ON RESEARCH ON EPIDEMIOLOGY AND COURSE OF ILLNESS

Both in classical German psychiatry and in the contemporary operationa lised diagnostic systems schizophrenia is conceptualised as a categori al disorder, the presence or absence of which can be verified dichotom ously. Empirical results, however, suggest that schizophrenia might be a dimensional disorder. The categorial perspective has advantages for epidemiological research; it produced important results like the find ing of a world-wide equal incidence of schizophrenia. Increasing impor tance is attributed to the definition of criteria, especially those of duration, which is arbitrary in many aspects. Results cf research con cerning the course of illness and sex distribution vary, depending on the definition of criteria, giving rise to different etiological hypot heses.