The remaining sites had already been factor analyzed, and for these, we used the published factor structures. Prior factor analysis of Lifetime Dimensions of Psychosis Scale (LDPS)(27) in the MGS sample, resulted in three factors: positive, negative, and mood (28). The UCLA sample utilized the Comprehensive Assessment of Symptoms and History (CASH)(29), and had been previously factor-analyzed using a larger sample than that included in the present GWAS (30), which resulted in a clinically meaningful five-factor model of positive, negative, disorganization, manic, and depressive symptoms.
