Pyramidical model of schizophrenia.

Research and treatment of schizophrenia have been impeded by its heterogeneity and the lack of well-standardized methods for a comprehensive assessment of symptoms, including positive and negative dimensions. To study symptom profiles, therefore, we standardized and administered a well-operationalized 30-item psychiatric symptom scale to 240 schizophrenic inpatients. Principal component analysis suggested a pyramidlike triangular model of uncorrelated but nonexclusive syndromes that encompassed the spectrum of psychopathology. Negative, positive, and depressive features constituted divergent points of a triangular base, and excitement made up a separate vertical axis. Paired syndromes could account for symptoms of the paranoid (positive-depressive), disorganized (positive-negative), and catatonic (negative-depressive) diagnostic subtypes. The transversal positions in this model suggested polarized dimensions in schizophrenia, including a prognostic axis (depression-cognitive dysfunction). The findings imply that (1) negative and positive syndromes show factorial validity and distinction from depression but, alone, are insufficient to accommodate the full diversity of symptoms; (2) schizophrenic subtypes derive from a hybrid between unrelated but co-occurring dimensions that may define the fundamental elements of psychopathology; and (3) the pyramidical model is of heuristic value. The results help to clarify the heterogeneity of schizophrenia and to illuminate the path toward syndrome-specific treatments.