Potential mechanisms of change in VR-CBT and standard CBT for schizophrenia-related paranoia: a mediation analysis from the FaceYourFears trial

Abstract Background and Hypothesis Cognitive models conceptualise paranoia in schizophrenia spectrum disorders (SSD) as driven and maintained by mechanisms, which can be targeted by cognitive behavioural therapy for paranoia (CBTp). This study examined potential mechanisms as mediators. Safety behaviours, belief inflexibility, and core beliefs about self and others were hypothesised to differentially mediate outcomes in virtual reality-based CBTp (VR-CBTp) and CBTp, with safety behaviours expected to be more influential in VR-CBTp, and belief inflexibility and self-related core beliefs in CBTp. Study Design This secondary analysis of the FaceYourFears trial included a per-protocol sample with complete data (VR-CBTp: n = 96; CBTp: n = 90). Groups were comparable, except for greater in-session exposure in VR-CBTp. Pearson correlations, linear regression analyses and structural equation modelling (SEM), examined each mediator separately. Causal inferences could not be drawn. Study Results Pearson correlations of change scores showed that positive safety behaviours and negative self- and others-related core beliefs were associated with paranoia across both interventions. Regression analyses without covariate adjustment showed no significant between-group differences, except for belief inflexibility (p = 0.041), which became non-significant with covariate adjustment (age, sex, depression). SEM showed no differential mediation effects. Conclusions No mediators differed between interventions, and no hypotheses were supported. These results suggest similar mechanistic pathways in CBTp and VR-CBTp. Treatment selection may instead best be guided by factors such as symptom profile, patient preference, accessibility, and engagement. Findings are discussed in relation to prior mediation studies within the field, with implications for future research.