Oxytocin and social cognition in patients with schizophrenia: comparison with healthy siblings and healthy controls

Objective: There is substantial evidence from animal research indicating a key role of the neuropeptide oxytocin (OT) in the regulation of complex social cognition and behaviour. Social cognition is indispensable for social relationships for the whole of human society, and numerous studies have shown impaired social cognition in schizophrenia (SCH) and unaffected first-degree relatives also seem to be impaired, albeit to a lesser extent. Because of that, this study focuses on the role of OT in social cognition in SCH. Methods: Twenty-seven patients with SCH, 27 healthy siblings (HS) of these patients, and 27 psychologically healthy controls (HC) were included in the study. Blood samples were collected through a peripheral venous catheter. Differences in the socio-demographical and WAIS-R were tested by chi-square and one way-ANOVA. To explore the relationships between social cognition and blood samples we performed Pearson correlations. MANCOVA (gender and WAIS-R as covariates) test was performed to investigate the effect of gender on blood levels of OT and WAIS-R on social cognition. Results: Significant differences were found in neurocognitive and social cognitive capacity but not in OT levels. In the healthy control group, there was a positive correlation between blood OT levels and RMET. There is a statistically significant difference between high and low OT groups with regard to social cognition in all subtests of the RMET. Conclusions: In the current study, we found that patients had deficits in social cognition and neurocognition. Lower endogenous OT levels are also predictive for poor social cognitive functioning in HS and HC.