IQ and subclinical psychosis: The role of psychosocial stressors and core schemata

Background and hypothesis: Previous research in both clinical and non-clinical populations has suggested an association between intelligence quotient (IQ) and psychosis. The social defeat hypothesis posits that low status and repeated humiliation increase the risk of psychosis. The present study investigated the relationship between IQ and subclinical psychosis in the general population, while also examining the potential mediating and confounding roles of psychosocial stressors and core schemata. Study design: We analyzed data from 1497 healthy controls in the EU-GEI dataset, a multicenter study conducted across six countries. IQ and the positive dimension of subclinical psychosis (measured by the positive dimension of the Community Assessment of Psychic Experiences questionnaire) were analyzed using linear regression models adjusting for age, sex, childhood trauma, stressful life events, and core schemata (positive and negative schemata). Mediation analysis was conducted to explore indirect effects. Study results: IQ was associated with subclinical psychosis. The results remained statistically significant after adjustment for several confounders. In the mediation analysis, IQ had no total or direct effect, but a small negative indirect effect through negative-other schemata (ß = -0.040; 95% Confidence Interval: -0.55, -0.024), childhood trauma (ß = -0.029; 95% CI -0.042, -0.016), negative-self schemata (ß = -0.009; 95% CI -0.017, -0.001), and stressful life events (ß = -0.012; 95% CI -0.021, -0.003). Conclusion: These findings support the idea that cognitive vulnerability is associated with an increased risk of subclinical psychotic symptoms, with psychosocial stressors and core schemata possibly playing a mediating role, in line with the social defeat hypothesis.