The epidemiology of onset and course of schizophrenia

Traditionally the heterogeneity of schizophrenia was dealt with by subdividing the syndrome into different subtypes. However, due to lacking standards, the result was an immense variety of subtypes partly based on cross-sectional assessments, partly taken the whole course between onset, resp. first admission and outcome after many years into account. Some solutions were based on symptomatology only, others also relied on social characteristics as the ability to fulfil different roles in family and the world of employment. So it is not surprising that the number of subtypes ranges from two up to more than 70. As one possible solution Carpenter and Kirkpatrick (1988) suggest that attempts to subdivide the schizophrenic syndrome should concentrate on few significant parts of the course thought of to represent specific disease processes. Based on two epidemiological studies finding about the onset, middle course and late course of schizophrenia are presented. In three quarter of the cases the onset of the first psychotic episode in schizophrenia is preceded by a prodromal phase with a mean length of about five years. The earliest signs of the disorder are depressive and negative symptoms. Early depressive symptoms predict higher overall symptom scores in the first illness episode and lower scores for affective flattening in the medium-term course. There is no decrease in the number of patients with acute symptomatology over fifteen years after first hospital admission, rather there is a tendency of an increase. With respect to social abilities we found a significant increase of disability over time. But the change already takes place during the first five years. Approx. 60% of those falling ill with schizophrenia become chronic and approx. 25% will recover during the first five to six years.