Background:
Cognitive models propose that cognitive and emotional processes, in the context of anomalies of experience, lead to and maintain delusions. No large-scale studies have investigated whether persecutory and grandiose delusions reflect differing contributions of reasoning and affective processes. This is complicated by their frequent cooccurrence in schizophrenia. We hypothesized that persecutory and grandiose subtypes would differ significantly in their associations with psychological processes.
Methods:
Participants were the 301 patients from the Psychological Prevention of Relapse in Psychosis Trial (ISRCTN83557988). Persecutory delusions were present in 192 participants, and grandiose delusions were present in 97, while 58 were rated as having delusions both of persecution and grandiosity. Measures of emotional and reasoning processes, at baseline only, were employed.
Results:
A bivariate response model was used. Negative self-evaluations and depression and anxiety predicted a significantly increased chance of persecutory delusions whereas grandiose delusions were predicted by less negative self-evaluations and lower anxiety and depression, along with higher positive self and positive other evaluations. Reasoning biases were common in the whole group and in categorically defined subgroups with only persecutory delusions and only grandiose delusions; however, jumping to conclusions, and belief flexibility were significantly different in the 2 groups, the grandiose group having a higher likelihood of showing a reasoning bias than the persecutory group.
Conclusion:
The significant differences in the processes associated with these 2 delusion subtypes have implications for etiology and for the development of targeted treatment strategies.