Multiple dimensions of schizotypy in first degree biological relatives of schizophrenia patients.

Considerable research has been devoted to identifying individuals predisposed to schizophrenia, with much of the effort devoted to identifying the personality characteristics of the biological relatives of schizophrenia patients. Although resource-consuming interviews have yielded promising results, investigators have long sought self-report measures that index genetic risk for schizophrenia. The Schizotypal Personality Questionnaire (SPQ) is a self-report measure that assesses the nine features of DSM-defined schizotypy. The SPQ, modified to include validity scales, was administered to 135 nonpsychotic first degree relatives of schizophrenia patients and 112 healthy controls. Principal components analysis (PCA) yielded three factors that correlated highly with previously reported factors (social-interpersonal, cognitive-perceptual, and disorganization). Social-interpersonal deficits were found to best differentiate relatives from controls. Contrary to the hypothesis that schizophrenia relatives are more defensive in responding to schizotypy questionnaires, relatives were significantly less defensive than controls. The results demonstrate that a multidimensional paper-and-pencil measure can characterize schizotypal features in schizophrenia relatives, which will be useful for the further delineation of the heritable schizophrenia spectrum phenotype.