Psychopathological dimensions in schizophrenia: a correlational approach to items of the SANS and SAPS

Seventy DSM-III schizophrenic patients were assessed for positive and negative symptoms using Andreasen's scales for the assessment of positive and negative symptoms (SANS and SAPS) on admission. The correlation structure of the items in the SANS and SAPS was explored in dimension and item levels by use of correlation plots through a distinct analytical method displaying the proximity matrix. The results revealed at least three major dimensions of symptoms delineated as Negative Symptoms, Disorganized Thoughts and Delusions and Hallucinations. The latter two dimensions were derived from the SAPS, while Negative Symptoms comprised most of the items in the SANS. Items in Disorganized Thoughts were more correlated to Negative Symptoms than to the other items in the SAPS. 'Loss of ego boundary' delusions and experience of auditory hallucinations appeared as two sub-clusters in the group of Delusions and Hallucinations. The relative independence of persecutory, grandiose, religious, somatic and reference delusions gives support to the concept that paranoid schizophrenia stands as a distinct clinical subtype of schizophrenia. The graphical method introduced here well expresses the information of correlation matrix and is useful for exploring inter-item or inter-cluster associations.