Reduced reliance on partner reciprocity drives lower trust in schizophrenia

Description: Schizophrenia is characterized by significant cognitive and social difficulties, including paranoid ideation and impaired trust in others. Despite consistent evidence of disrupted social interactions in schizophrenia, the neurocognitive mechanisms driving these impairments remain poorly understood. Here, we tested the hypothesis that schizophrenia is associated with altered neural processing of others’ cooperative behavior, leading to disrupted belief formation and reduced trust. In a sample of individuals with a diagnosis of schizophrenia (N=39) and healthy controls (N=39) playing a computerized investment game, we show that individuals affected by schizophrenia trusted their game partners less, which was due to reduced sensitivity to partner reciprocity and greater variability in trust behavior. Computational modeling shows that, while both groups learned the partner’s behavior equally well, individuals with schizophrenia were less likely to act on their beliefs about partner benevolence. Neuroimaging results show that during encoding of partner reciprocity, the putamen was more engaged and functionally connected with the precuneus in healthy controls. Reduced functional connectivity between putamen and precuneus was further associated with less successful trusting interactions (lower payoffs) in individuals with schizophrenia as compared with control participants. These results indicate that reduced belief reliance (acting less on formed beliefs about others) rather than impaired belief formation drives distrust in clinical populations.