Psychometric properties of the Brief Version of the Schizotypal Personality Questionnaire in relatives of patients with schizophrenia-spectrum disorders and non-psychiatric controls

The Schizotypal Personality Questionnaire-Brief Version (SPQ-B), which includes cognitive-perceptual, interpersonal, and disorganized domains, was developed as a concise, self-report measure of schizotypy. This analysis was conducted to: (1) determine the internal consistency reliability of SPQ-B total and subscale scores, (2) use confirmatory factor analysis to assess the three-factor model as well as a single-factor solution, and (3) examine a measure of concurrent criterion validity of SPQ-B scores. The study was conducted at a large, urban, university-affiliated, public-sector health system in the southeastern United States. Data were obtained from 118 participants, including 61 biological relatives of patients with schizophrenia, schizoaffective disorder, or schizophreniform disorder, and 57 non-psychiatric controls. Relatives and controls did not differ significantly on SPQ-B total or subscale scores (or on the full 74-item SPQ total or subscale scores). Internal consistency reliability was adequate for the total SPQ-B score and the interpersonal subscale but was less than ideal for the cognitive-perceptual and disorganized subscales. Regarding the confirmatory factor analysis, though the three-factor solution yielded reasonably good fit to the data, the single-factor solution provided equal fit. Correlations between the three subscales ranged from .63 to .74. With regard to criterion validity, correlations between the SPQ-B total and subscale scores and schizotypy scores derived from a semi-structured, interview-based assessment revealed correlations generally ranging from .40 to .60. The SPQ-B may be a useful brief screening measure of schizotypy, though some limitations in its psychometric properties were evident in this sample. It may be advisable to use total SPQ-B scores rather than subscale scores in some situations, or to use factor analytic techniques to study the instrument's latent structure in specific samples.