Harmful grandiose delusions: developing a cognitive model

Thesis

Background

Grandiose delusions are inaccurate beliefs about having special powers, wealth, mission, or identity. They are a common psychotic experience, but neglected as a specific focus of research. There is no evidence-based theoretically driven psychological intervention for harmful grandiose delusions.

Aims

The thesis aimed i) to determine the extent to which patients identify harmful consequences occurring as a result of grandiose delusions and whether they want help with these harms, and ii) to develop a theoretical causal model of grandiose delusions and conduct preliminary tests of the model.

Method

A qualitative study is reported in which fifteen patients with experiences of grandiose delusions were interviewed. Thematic analysis and grounded theory were used to analyse the data (Chapter 2). Analyses are also reported from cross-sectional questionnaire data collected from two non-clinical cohorts (n=13,323) and a clinical cohort of 798 patients with a psychosis diagnosis, 375 of whom had grandiose delusions (Chapters 3-5).

Results

More than three-quarters of patients with grandiose delusions identified grandiose-related harms occurring in the past six months. Over half of patients wanted help with these difficulties. Six putative maintenance factors for grandiose delusions were identified. Tests of association found that in the clinical group, the meaning of grandiose delusions, repetitive thinking about the grandiose belief, immersion behaviours, and daydreaming accounted for 53.5%, 20.4%, 39.5%, and 19.1% of the variance in grandiosity severity respectively.

Conclusions

Most patients with grandiose delusions identify difficulties arising from their grandiose delusions, which may provide a route for engagement in treatment. Potential maintenance mechanisms that may be suitable targets for intervention include the meaning of the grandiose delusions, immersion behaviours, perseverative thinking, and pleasant daydreams. If these findings are verified by further longitudinal and experimental research, this would enable the development of a specific cognitive-behavioural intervention for people with harmful grandiose beliefs.

Authors: Isham, L

• DOI: 10.5287/ora-zv8j9jrap
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: psychosis; cognitive model; grandiose delusions
• Subjects: Psychology