Replication of the 3-factor model by Liddle to a population-related first-episode sample of schizophrenic patients

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 t he ABC-Schizophrenia-Study. The three-factor-model of Liddle with three fac tors (psychomotor poverty, disorganisation, reality distortion) was replica ted for the time at first admission. The model is also valid for first-epis ode-patients as well as to chronic patients. The comparison of the three-fa ctor-model of Liddle with Crow's dual process model, Andreasen's bipolar mo del and the "severity-liability" model was done by means of confirmatory fa ctor analysis. The comparison shows that at first admission, the three-fact or-model fitted in best with the data. In contrast to previous analyses wit hin the ABC-Study, in which positive correlations have been found between p ositive and negative symptoms, no positive correlation exists between Liddl e's negative and positive dimensions. This may be the consequence of the su bdivision 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. Ther e are no associations between sex, type of onset, age at onset and the thre e dimensions of Liddle's model. Patients with the familial load are more di sorganized and patients with obstetric complications show more negative sym ptoms. While the negative dimension shows a high stability over five years, the dimensions "disorganisation" and "positive symptoms" are not stable ov er time. However, there is a high degree of correlation for the dimensions "disorganization" and "positive symptoms" among cross-sections while the ne gative dimension was independent of the other two dimensions. The negative dimension is a highly significant predictor for social disability and socia l development over five years, whereas the dimensions "disorganization" and "positive symptoms" have no prognostic importance for the outcome in the l ong term.