The dimensions of schizophrenia phenomenology - Not one or two, at least three, perhaps four

Background. This confirmatory investigation examined the underlying structure of schizophrenia phenomenology through examination of the fit of several prominent dimensional models to observed symptom data. Method. Confirmatory factor analysis was conducted on a correlation matrix of schizophrenia signs and symptoms derived from case history ratings of 192 individuals with schizophrenia who were the subjects in the major twin studies of schizophrenia. Results. Schizophrenia phenomenology appears best described by four underlying factors, namely negative symptoms, premorbid social adjustment deficits, reality distortion, and disorganisation. Of interest, the premorbid deficit dimension was directly associated with negative symptoms and disorganisation, but was inversely associated with reality distortion. Conclusions. These data clearly support the multidimensionality of schizophrenia phenomenology and provide objective support for a four-factor model over other models. This four-factor model may be useful in organising existing and future data concerning the genetic, neurobiological, neurological, and psychosocial features of schizophrenia.