Self-referential information processing in psychotic disorders

Abstract

Motivations Ideas and delusions of reference (I/DOR) are common psychotic symptoms and can be defined as self-referential experiences in excess of the amount of evidence available in the immediate environment. A putative neurocognitive mechanism is increased automatic attention capture by self-referential (SR) information. This study was carried out to test the hypotheses that 1) compared with patients with no I/DOR, those who have the symptom have increased attentional shift to SR information and 2) there is a positive correlation between the severity of I/DOR and the extent of attentional shift to SR information. Clinical and cognitive correlates of I/DOR were also explored.

Methods Patients with I/DOR (n=20, mean age 25.2±7.9 years, 4 men) and without I/DOR (n=17, mean age 28.6±8.2 years, 10 men) matched for age and education were assessed for positive symptoms, negative symptoms, mood symptoms and basic neurocognition. I/DOR were phenomenologically assessed using the Ideas of Reference Interview Scale (IRIS). In an interference task, patients were instructed to respond to computerized Stroop tasks while ignoring a voice clip presented binaurally with the subject’s own name (SON) embedded in certain trials. Within-subject differences in reaction time and accuracy between Stroop trials with and without SON were used as parameters to measure the degree of attentional shift to SR information.

Between-group and within-subject differences in the reaction time and accuracy in the interference task were analysed using 2×2 mixed-ANOVA. Bivariate correlation was used to explore the relationship between IRIS scores and performance in the interference task. Stepwise linear regression analysis was used to explore the correlates of I/DOR.

Results There was statistically significant interaction between conditions with and without SON and patient groups on the reaction time of the interference task (p=0.048). Simple main effects showed the mean difference of reaction time between conditions with and without SON was statistically significant in patients with I/DOR (p=0.001) but not in patients without I/DOR (p=0.862). Parameters used in the interference task correlated highly with IRIS global score and subscores on pervasiveness, self-referential discrepancy, conviction and frequency (r=0.328-0.517, range; p<0.05), unaltered by other clinical and cognitive variables except depressive symptoms and social anxiety. Regression analysis showed that I/DOR were related to depressive symptoms, social anxiety and attentional shift to SON.

Discussion The significant interaction and simple main effect suggest that I/DOR are associated with a heightened attentional shift to SR information. The robust correlations between IRIS scores and attentional shift to SON provide some evidence to support the continuum hypothesis of I/DOR. The possible roles of emotions in the pathogenesis of I/DOR are discussed.

Significance With the use of well-matched patient samples and an ecologically valid paradigm based on known human cognitive functions, the present study provided first empirical evidence for a theoretical link between cognitive anomaly and a key psychotic symptom. The SON paradigm provides a promising tool for further research and can potentially be developed into a neurocognitive parameter of I/DOR. The present study also shed light on the complexity of I/DOR in relation to other symptoms to inform future studies.