Psychopathological dimensions in first-episode psychoses

Background: Dimensional frameworks for structuring psychopathology have been formulated in recent years to overcome classification problems of categorical approaches. However, few studies have addressed the dilemma of hierarchy within symptoms or dimensions in psychosis. Methods: This study was designed to examine the hierarchical structure of psychopathological dimensions in first episode psychosis. The sample consisted of 94 first-episode patients psychosis. An exhaustive psychopathological assessment was carried out using the AMDP-system. Consecutive principal component analyses of AMDP symptoms, determining ‘a priori’ the number of factors to be extracted, were carried out. Results: Following the track of the resulting factor analyses, a ‘vertical hierarchical’ framework was achieved. Our schema organized dimensions in a series of echelons in which lower tiers are subsumed as subsets of those assigned to higher ranks. In addition, a final model comprising 10 dimensions provided an ‘horizontal’ and multidimensional structure comprising all relevant psychopathological dimensions in first-episode psychosis. Conclusions: This study confirmed to a great extent the existence of a hierarchical organization within psychopathological dimensions in ‘first-episode’ psychosis. The present ‘hierarchical and multidimensional’ model of psychopathological dimensions allows for selection of the level of complexity of ‘candidate phenotypes’ to use in neurobiological research of psychosis.