REVISITING THE FACTOR STRUCTURE FOR POSITIVE AND NEGATIVE SYMPTOMS - EVIDENCE FROM A LARGE HETEROGENEOUS GROUP OF PSYCHIATRIC-PATIENTS

Objective: The factor structures of individual positive and negative s ymptoms as well as global ratings were examined in a diagnostically he terogeneous group of subjects. Method: Subjects were identified throug h a clinical and family study of patients with major psychoses at a VA medical center and evaluated with the Scale for the Assessment of Neg ative Symptoms and the Scale for the Assessment of Positive Symptoms. For the examination of global-level factor structures (N=630), both pr incipal-component analysis and factor analysis with orthogonal rotatio n were used. Factor analysis was used for the examination of item-leve l factor structures as well (N=549). Results: The principal-component analysis of global ratings revealed three factors: negative symptoms, positive symptoms, and disorganization. The factor analysis of global ratings revealed a negative symptom factor and a positive symptom fact or. The item-level factor analysis revealed two negative symptom facto rs (diminished expression and disordered relating), two positive sympt om factors (bizarre delusions and auditory hallucinations), and a diso rganization factor. Conclusions: The generation of additional meaningf ul factors at the item level suggests that important information about symptoms is lost when only global ratings are viewed. Future work sho uld explore clinical and pathological correlates of the move different iated item-level symptom dimensions.