Repetitive behaviors in schizophrenia: a single disturbance or discrete symptoms?

Schizophrenia patients often display multiple repetitive behaviors. We investigated relations among nine repetitive behaviors and evaluated the hypothesis that these behaviors are varied manifestations of a single underlying biobehavioral disturbance. Nine repetitive behaviors from the Elgin Behavioral Rating Scale were assessed in 400 schizophrenia patients residing at a state hospital. A majority of patients were smokers (76.3%) and very few had pica (3%). Several other repetitive behaviors showed substantial frequency. A principal components analysis revealed eight of nine behaviors shared at least 10% of their variance with a single, common component. However, a principal factor analysis suggested a five-factor model best represented the data. The five factors and items identifying them were: (1) 'oral consumption' behaviors-polydipsia and smoking; (2) 'Kluver-Bucy' behaviors-bulimia and hypersexuality; (3) 'movement' behaviors-mannerisms/postures and pacing; (4) 'bizarre use of objects'-bizarre grooming and hoarding; (5) 'Pica'. Associations among repetitive behaviors varied. Symptoms such as smoking and polydipsia appeared reliably related, and others such as pica appeared discrete and independent. Overall, the data did not support the 'single disturbance' hypothesis and suggested a multifactorial model is needed to characterize repetitive behavior disturbances in schizophrenia.