[Dimensions of schizophrenic symptomatology. Comparative testing of several theoretical models in a first-episode...

The issue of this study was the investigation of the dimensional structure of non-psychotic and psychotic symptoms in 232 first-episode schizophrenic patients (ICD-9 295., 297., 298.3, 298.4). The study was conducted within the ABC-Schizophrenia-Study. The three-factor-model of Liddle with three factors (psychomotor poverty, disorganisation, reality distortion) was replicated for the time at first admission. The model is also valid for first-episode-patients as well as to chronic patients. The comparison of the three-factor-model of Liddle with Crow's dual process model, Andreasen's bipolar model and the "severity-liability" model was done by means of confirmatory factor analysis. The comparison shows that at first admission, the three-factor-model fitted in best with the data. In contrast to previous analyses within the ABC-Study, in which positive correlations have been found between positive and negative symptoms, no positive correlation exists between Liddle's negative and positive dimensions. This may be the consequence of the subdivision of the positive dimension into the two dimensions disorganisation and psychotic symptoms. As within the three-factor-model only the negative dimension and disorganisation correlated weekly, the three dimensions are best viewed as relatively independent for the time at first admission. There are no associations between sex, type of onset, age at onset and the three dimensions of Liddle's model. Patients with the familial load are more disorganized and patients with obstetric complications show more negative symptoms. While the negative dimension shows a high stability over five years, the dimensions "disorganisation" and "positive symptoms" are not stable over time. However, there is a high degree of correlation for the dimensions "disorganization" and "positive symptoms" among cross-sections while the negative dimension was independent of the other two dimensions. The negative dimension is a highly significant predictor for social disability and social development over five years, whereas the dimensions "disorganization" and "positive symptoms" have no prognostic importance for the outcome in the long term.