Validation of the Prodromal Questionnaire-Brief in a representative sample of adolescents: Internal structure, norms, reliability, and links with psychopathology.

OBJECTIVES: The main purpose of the present study was twofold: to validate the Prodromal Questionnaire-Brief (PQ-B) in a community-derived sample of adolescents and to examine the links between psychotic-like experiences and emotional and behavioral problems, prosocial behavior, suicidal ideation, and bipolar-like experiences.
METHOD: One thousand five hundred eighty-eight students selected by random sampling participated in a cross-sectional survey. The PQ-B, Paykel Suicide Scale, Strengths and Difficulties Questionnaire, Mood Disorder Questionnaire, Penn Matrix Reasoning Test, Family Affluence Scale-II, and Oviedo Infrequency Scale were used.
RESULTS: The unidimensional factorial structure of the PQ-B items showed adequate goodness of fit index. This model also showed configural and strong invariance across gender. The internal consistency of the PQ-B total frequency score was 0.92. A high degree of overlap was found between psychotic-like experiences and emotional and behavioral problems, suicidal ideation, and bipolar-like experiences.
CONCLUSION: The PQ-B is a brief, easy, and reliable tool for screening psychotic-like experiences in adolescents from the general population. The assessment of risk for psychosis and its relationship with other psychopathological risk factors in a close-in strategy or two-stage process model may help us to enhance the early identification for youths at heightened risk for serious mental disorders.