Psychometric properties of the schizotypal personality questionnaire-brief revised (SPQ-BR) in a German-speaking sample

Schizotypy refers to personality traits linked to an increased risk for schizophrenia-spectrum disorders (SSD). The Schizotypal Personality Questionnaire-Brief Revised (SPQ-BR) is a widely used 32-item self-report measure, but its psychometric properties in German-speaking populations are unexplored. This study comprised 738 individuals, including 33 with SSD, and 148 with other mental disorders. Participants (mean age: 38 years, 77% female) completed an online survey that included the German version of the SPQ-BR (SPQ-BR-G) and additional measures to assess convergent and discriminant validity. Reliability, latent factor structure, and validity were assessed. The SPQ-BR-G demonstrated excellent internal consistency (α = 0.91), good convergent validity (r = 0.52-0.58), and discriminant validity (r < 0.50) for the cognitive-perceptual and disorganized factors. Confirmatory factor analysis supported three- and four-factor solutions, while a single-factor model demonstrated poor fit. Subjective well-being was negatively associated with the SPQ-BR-G, after adjusting for sex, age, and education. Compared to the survey sample, SSD patients scored significantly higher on all factor levels and most items (p < 0.05), with 35% ranking in the top SPQ-BR-G decile. In SSD patients, moderate to high correlations were observed between the negative (r = 0.86, p < 0.001) and positive (r = 0.53, p < 0.05) dimensions of the Positive and Negative Syndrome Scale and the SPQ-BR-G. The SPQ-BR-G shows robust psychometric properties, supporting its use in schizotypy research. Its validation enhances cross-cultural comparisons and may aid in early risk and biological risk factor identification for SSD.