Integrating psychopathological dimensions in functional psychoses: a hierarchical approach

Previous factor analysis studies of psychotic symptomatology have demonstra ted three psychopathological dimensions: positive, negative and disorganiza tion. However, few studies have analyzed non-schizophrenic samples and most use a syndrome-level of analysis or only schizophrenic symptom scales. Thi s study examined how many dimensions underlie psychosis, and whether within psychosis there is a hierarchical organization of dimensions. A total of 660 inpatients with an acute psychotic episode were studied. Psy chopathology was measured through a wide psychopathological assessment usin g the Manual for the Assessment and Documentation of Psychopathology (AMDP- system). Principal component factor analysis was carried out on 64 psychopathologica l symptoms scoring 1 or higher in at least 10% of the sample. A 15-factor s olution was obtained which failed to depict a psychosis model on clinical a nd methodological grounds. Further predetermined factor analyses ranging fr om 1 to 15 factors were carried out to examine alternative factor solutions . A 10-dimensional model was the best model on clinical, statistical and co nceptual grounds. Moreover, the examination of the 1 to 10 dimensional mode ls allowed us to infer a hierarchical model of psychopathological dimension s, which can be represented in the frame of a tree-structure. The model per mitted transitions between psychiatric categories and psychopathological di mensions, and it was able to integrate previous factor solutions with diffe rent numbers of resulting dimensions. The findings have implications for the design of future studies and for the hierarchical conceptualization of psychopathological dimensions. (C) 2001 Elsevier Science B.V. All rights reserved.