Dimensions of major psychoses: a confirmatory factor analysis of six competing models.

The symptoms of major psychosis aggregate in factors. Models of one to eight dimensions have been reported. In the present study, we tested six competing factor models, based on the psychotic and affective items of the OPCRIT checklist, in a large sample (N = 1294) of patients diagnosed with DSM-IV schizophrenia (n = 460), bipolar disorder (n = 726) and delusional disorder (n = 108). Confirmatory factor analysis was used to test the following models: (1) unique psychotic dimension; (2) positive-manic items, negative-depressive items; (3) model 2 with the addition of a disorganized factor; (4A) positive, negative, depressive and manic dimensions; (4B) model 4A with loss of pleasure (Anhedonia) and loss of energy (Apathy) included among depressive instead of negative symptoms; and (5) same as model 4B except for the addition of a disorganized domain. The four- and five-factor models fit the data much better than simpler ones. Between the two four-factor models, M4B emerged as more appropriate than M4A. The five-factor solution (M5) displayed the best fit. In conclusion, our confirmatory factor analysis in a large sample of psychotic subjects indicated that the symptomatology of major psychoses is composed of the following five factors: mania, positive symptoms, disorganization, depression and negative symptoms. Copyright 2004 Elsevier Ireland Ltd.