Delusional beliefs: Exploring associated cognitive and emotion factors

Systematic Review:
Objectives
Grandiose Delusions (GD) are described as false beliefs about a special identity or inflated sense of power, worth or knowledge. Theoretical understandings of psychological factors associated with GD remain inconclusive. The review aimed to explore the current literature on GD, focusing specifically on associated emotion factors.
Methods
Following a published protocol (PROSPERO ID: CRD42024505574), a systematic review was completed in January 2024 across PsycINFO, MEDLINE and Scopus to identify quantitative studies reporting on emotion factors related to GD, in adults. Methodological quality and risk of bias for included studies was evaluated using an appraisal tool and a narrative synthesis was carried out.
Results
Twenty-one studies were included in the final narrative synthesis. Large methodological heterogeneity was present within studies and methodological quality varied. Eight emotion factors were identified with depression, anxiety and self-esteem being the most commonly explored. Relationships between emotion factors and GD were inconsistent across studies, particularly for self-esteem, however, there appeared to be some support for a link with lower levels of depression and no link with increased anxiety.
Conclusions
The review highlighted a scarcity of research exploring emotion factors associated with GD and limitations with study designs prevented the exploration of causality. Given the heterogeneity and varying methodological quality caution is required within interpretation. Better-quality research utilising experimental and longitudinal study designs is needed to understand the role of emotion in the formation and maintenance of GD. Greater understanding would support with identifying at-risk populations and the development of interventions for use within clinical practice.

Empirical:
Objectives
Impairments in judgements of certainty have been suggested as a potentially underlying mechanism associated with delusional beliefs. This study aimed to explore the relationships between certainty judgments, compared with both response accuracy and associated response time (RT), predicting differences for individuals who experience delusional beliefs. The study also aimed to explore whether threat vs neutral question content impacted these relationships.
Methods
A between-groups cross-sectional design was implemented. Groups included patients experiencing delusional beliefs (n=22), and mental health (n=22) and general population (n=22) controls. Participants rated their certainty in attitudes towards neutral items and future events and also answered 12 threat and 12 neutral content multiple-choice general knowledge questions, with RT and self-rated certainty also being collected.
Results
Accuracy was found to positively correlate with self-rated certainty, with a non-significant weaker correlation identified for threat questions. Participants experiencing delusional beliefs had significantly lower accuracy scores but did not significantly differ in their certainty ratings compared to controls for both correct and incorrect responses.
Significant differences were found between groups for the relationship between RT and certainty ratings. Negative relationships between certainty ratings and RTs were found for both controls but not for patients experiencing delusional beliefs, regardless of question type (threat/neutral).
Conclusions
Findings suggest certainty judgments do not appear to differ for patients experiencing delusional beliefs regarding answer accuracy, but they do appear to differ for corresponding RTs. Question type (threat/neutral) was not found to significantly impact relationships. Future research should look to replicate findings in larger clinical samples.