Edinburgh Napier University

  Background
An influential psychological model of persecutory delusions proposed they are caused by a bias towards holding others responsible for negative events, which serves to prevent underlying low self-esteem from reaching awareness. An early (1994) version of the model predicted self-esteem would therefore be preserved in people with these delusions, whereas a later (2001) version suggested it would be unstable, and that there would be a discrepancy between their explicit and implicit self-esteem, with the latter being lower. Our aim was to perform the first comprehensive meta-analytical test of the key predictions of this model, taking into account evidence quality.
Methods
Reports identified in previous systematic reviews were collated. Electronic databases (i.e., PsycINFO, MEDLINE, EMBASE and Web of Science) were searched from 2012 to September 2016. The review was pre-registered (PROSPERO registration number: CRD42016032782). Cross-sectional data from case-control, longitudinal or experimental studies that examined self-esteem or the externalising attributional bias in individuals diagnosed with schizophrenia-spectrum disorder were eligible for meta-analyses of group differences, but only if at least 50% of participants with psychosis also had current persecutory delusions. Uncontrolled and longitudinal studies were included in meta-analyses of correlations and self-esteem instability, respectively. Study and outcome quality were assessed using the Agency for Healthcare Research and Quality (AHRQ) assessment tool, and a modified version of Grading of Recommendations Assessment, Development and Evaluation (GRADE), respectively.
Results We screened 3053 records, examined 104 full-text reports, and included 64 eligible studies. Consistent with the predictions of both versions of the model, paranoia severity in psychosis was positively correlated with the degree of externalising attributional bias (k=21, N=1128, r=0.18, 95% CI 0.08, 0.27; moderate quality). People with persecutory delusions also had a greater externalising attributional bias compared to non-clinical (k=27, N=1442, g=0.48, 95% CI 0.23, 0.73; moderate quality) and depressed individuals (k=10, N=421, g=1.06, 95% CI 0.48, 1.63; moderate quality), and those with psychosis without persecutory delusions (k=11; N=480; g=0.40, 95% CI 0.12, 0.68; moderate quality). Contrary to the 1994 version’s predictions, paranoia severity in psychosis was negatively correlated with explicit self-esteem (k=23, N=1866, r=-0.26, 95% CI -0.34, -0.17; high quality). People with persecutory delusions also had lower explicit self-esteem than non-clinical individuals (k=22, N=1256, g=-0.88, 95% CI -1.10, -0.66; high quality) and similarly low explicit self-esteem to people with psychosis without persecutory delusions (k=11; N=644, g=-0.26; 95% CI -0.54, 0.02; moderate quality). Consistent with the 2001 version’s predictions, self-esteem instability was positively correlated with paranoia severity in psychosis (k=4, N=508, r=0.23, 95% CI 0.11, 0.34; high quality), and people with persecutory delusions had a greater discrepancy between their implicit and explicit self-esteem than depressed individuals (k=7, N=398, g=0.61, 95% CI 0.37, 0.85; moderate quality). They had higher explicit self-esteem than depressed individuals (k=13, N=647, g=0.89, 95% CI 0.51, 1.28; moderate quality), but similarly low implicit self-esteem (k=7, N=398, g=-0.19, 95% CI -0.45, 0.07; very low quality). Contrary to this later version’s predictions, they did not have a greater self-esteem discrepancy than non-clinical individuals (k=10; N=592; g=-0.17; 95% CI -0.45 to 0.12; very low quality). There were also no differences between people with psychosis with or without persecutory delusions in implicit self-esteem (k=4; N=167; g=-0.24, 95% CI -0.77, 0.30; low quality) or self-esteem discrepancies (k=4; N=165; g=0.17, 95% CI -0.19, 0.53; moderate quality).
Interpretation Our meta-analytical appraisal of 25 years of research found that, as predicted by the most recent version of the defensive model of persecutory delusions, people with these delusions show an externalising attributional bias, that this and their self-esteem instability are associated with greater paranoia severity, and that they have a greater implicit-explicit selfesteem discrepancy than people with depression. Its predictions that they would have a greater
self-esteem discrepancy than non-clinical individuals and people with psychosis without persecutory delusions were not supported, nor was the prediction of the earlier version of the model, that self-esteem would be preserved in persecutory delusions. To overcome the limitations of the observational data we reviewed, experimental studies, which may at some stage include interventionist-causal trials, are now required.