The common matrix of major psychoses

Background. In the last years, research on the psychopathological dimensions of the schizophrenic spectrum and the depressive disorders led to the identification of a variable number of factors. Whereas many are the studies on the dimensions of schizophrenia and mood disorders, few studies showed a dimensional overlap between the two psychopathological areas and no study used diagnosis-specific rating scales on samples with different than target diagnoses. The objective of this study was to re-examine the factor structure emerging from the analysis of two patient samples, one affected by schizophrenic spectrum disorders and the other from depressive disorders, using for both samples the same assessment tools (Hamilton Depression Rating Scale [HAM-D] and Positive And Negative Syndrome Scale [PANSS]). Materials and Method. We studied a sample of 254 patients, 131 with a schizophrenic and 123 with a depressive spectrum diagnosis according to the DSM-IV criteria. Patients were referred to the Outpatient facility of the III Psychiatric Clinic of the University of Rome, ≪La Sapienza≫. The entire sample was assessed through the completion of the PANSS e the HAM-D. Data were analysed through factorial analysis based on symptom correlation according to their level of severity (between-symptoms co-variance). Results. In the group of schizophrenic spectrum disorders, factorial analysis yielded four factors for the PANSS, Impoverishment, Reality distortion, Depression/Anxiety, Excitement and four also for the HAM-D, Anxiety, Insomnia, Depression, Reality distortion. In the group of depressive spectrum disorders four factors were extracted from the HAM-D, i.e., Depression, Anxiety, Reality distortion, Insomnia and three from the PANSS, i.e., Impoverished affect, Reality distortion and Anxiety. The factor structure analysis of the combined PANSS and HAM-D items led to the identification of four factors in the group with schizophrenic spectrum disorders, i.e., Impoverishment, Reality distortion, Affect/Mood, Anxiety and four factors in the group with depressive spectrum disorders, Impoverished affect, Reality distortion, Depression and Anxiety. The factor structure analysis of the combined items of the two scales in the overall sample led to the identification of four factors: Impoverishment, Reality distortion, Anxiety and Depression. Conclusions. Factorial analysis identified four factors that allow to analyse and represent the two syndrome cluster groups as if they belong to the same psychopathological area. The results of this study show that all identified dimensions for schizophrenia are present in mood disorders and vice versa. What is different is the relative ≪weight≫ of every factor in the two syndrome areas. It is the different degree of association of these dimensions and the different ≪load≫ on the patient of each of these that determines the specific clinical picture. All these considerations confirm the importance of a dimensional approach to psychopathology based on dimensional co-morbidity, as opposed to a categorical approach.