A preliminary investigation into theory of mind and attributional style in adults with grandiose delusions.

INTRODUCTION A preliminary cognitive model of grandiose delusions has been put forward suggesting that persecutory and grandiose delusions shared distinct, yet overlapping psychological processes. This study aims to test this model and hypothesises that participants experiencing grandiose delusions may demonstrate a theory of mind (ToM) impairment and differences in attributional style compared to a control group. METHODS A cross-sectional design compared the performance of 18 individuals with grandiose delusions to a control group of 14 participants with depression. ToM was measured using a non-verbal joke appreciation task and a verbal stories task. Attributional style was measured using the internal, personal and situational attributions questionnaire. RESULTS Participants experiencing grandiose delusions performed significantly worse on both ToM tasks compared to controls. Furthermore, these participants provided significantly more atypical answers when explaining the joke behind the ToM cartoons. No differences for subjective funniness ratings or attributional style were found. CONCLUSIONS This preliminary study indicated participants experiencing grandiose delusions have ToM impairments which may contribute to the maintenance of this symptom.