Oxytocin mediates self-other and inevitability asymmetries in high-conflict moral judgment in schizophrenia

Schizophrenia is characterized by social cognition deficits, yet the neurobiological mechanisms of moral reasoning remain poorly understood. In particular, self-other differentiation and contextual sensitivity, reflected in moral asymmetries during high-conflict dilemmas, have been underexplored in relation to oxytocin, a key neuropeptide implicated in social cognition.

We recruited 58 individuals with schizophrenia and 31 healthy controls. Participants completed a validated set of high-conflict personal moral dilemmas, varying by perspective (self vs. other) and harm evitability (inevitable vs. evitable). Plasma oxytocin levels were measured, and group differences in moral judgments were examined using mixed ANCOVA, followed by mediation analyses testing oxytocin as a mediator of group effects on self-other discrepancy and inevitability asymmetry.

Individuals with schizophrenia showed lower plasma oxytocin levels than controls. Whereas controls endorsed more utilitarian choices in inevitable than evitable contexts, individuals with schizophrenia failed to show this inevitability effect. Group differences in self-other discrepancy were not behaviorally significant; however, mediation analysis revealed a significant indirect-only effect via plasma oxytocin, with lower oxytocin associated with reduced self-other asymmetry. In contrast, disruption of the inevitability effect was partially mediated by oxytocin.

Our findings support a potential role for oxytocin-related mechanisms linking schizophrenia to altered moral asymmetries. Oxytocin showed an indirect-only association with self-other perspective sensitivity, without a direct behavioral group difference, and partially mediated impaired sensitivity to contextual inevitability. These results suggest oxytocin contributes to the social-cognitive basis of moral decision-making in schizophrenia, indicating a potential therapeutic target for social dysfunction.