Prediction of psychopathology and functional impairment by positive and negative schizotypy in the Chapmans' ten-year longitudinal study.

The present study examined the predictive validity of psychometrically assessed positive and negative schizotypy in the Chapmans' 10-year longitudinal data set. Schizotypy provides a useful construct for understanding the etiology and development of schizophrenia and related disorders. Schizotypy and schizophrenia share a common multidimensional structure that includes positive and negative symptom dimensions. Recent cross-sectional studies have supported the validity of psychometric positive and negative schizotypy; however, the present study is the first to examine the predictive validity of these dimensions. The Chapmans' longitudinal data provided an ideal opportunity because of the large sample size, high reassessment rate, and extended interval between assessments. A total of 534 psychometric high-risk and control participants were initially assessed, and 95% of this sample was reinterviewed 10 years later. As hypothesized, positive and negative schizotypy uniquely predicted the development of schizophrenia-spectrum disorders. At the reassessment, both positive and negative schizotypy predicted psychotic-like, schizotypal, and paranoid symptoms, as well as poorer adjustment. The positive dimension was associated with mood and substance use disorders and mental health treatment. Negative schizotypy was associated with schizoid symptoms and social impairment at the follow-up. The results extend the growing validity findings for psychometrically assessed positive and negative schizotypy by demonstrating that they are associated with the development of differential patterns of symptoms and impairment.