Core schema instability in youth at clinical high risk for psychosis: within-person variability as an index of self-belief precision

Aim. Core schemas are considered stable traits in clinical high risk (CHR) research. However, unexamined fluctuation may conceal belief changes that precede psychosis emergence. We examined whether schemas possess considerable within-person variability in CHR, and whether that variability exceeds that of controls. Methods. In NAPLS 2, 411 CHR and 194 control participants completed the Brief Core Schema Scales (BCSS) at least three times across 24 months. Random-intercept models identified intraclass correlations in CHR. Bayesian censored location-scale models, correcting for floor scores and mean level differences, compared within-person SD between groups. Results. Within-person variance accounted for 41.3% to 50.6% of BCSS variance in CHR. Latent within-person SD was greater in CHR on all four subscales, most for negative-self (ratio 1.71, 95% CrI [1.50, 1.94]). This variability was largely independent of shared improvement and psychotropic medication effects. Conclusions. Core schemas fluctuate substantially in CHR compared to controls, particularly in negative self-beliefs. Single baseline scores may understate associations between schemas and outcomes.