BACKGROUND - Social impairments are a hallmark feature of schizophrenia and are a key predictor of functional disability. Deficits in social information processing likely underlie social impairment; however, this relationship is understudied. We previously demonstrated that patients with schizophrenia fail to habituate to neutral faces, providing evidence for an alteration in basic social information processing. It remains unknown whether patients with schizophrenia also show deficits in processing of more complex social information. Out-group bias provides an excellent opportunity to test complex social information processing because the bias requires basic face processing skills, the ability to discriminate between groups, as well as the ability to categorize oneself into a salient social group.
METHODS - Study participants were 23 patients with schizophrenia and 21 controls. Using functional magnetic resonance imaging, habituation of response to 120 s of repeated presentations of faces was assessed in participants who viewed either same-gender faces or opposite-gender faces. The interaction between face gender (same/opposite) and group was examined in three key regions: amygdala, hippocampus, and visual cortex. Social impairment was measured using the PANSS and correlations between social impairment and out-group effect (main effect of face type) were performed in patients.
RESULTS - Patients with schizophrenia had aberrant neural responses to opposite-gender faces (interaction, p<.05 corrected). Healthy controls showed an immediate heightened response to opposite-gender faces relative to same-gender faces; but in patients this effect was substantially delayed (~70s). In patients with schizophrenia, the out-group bias was significantly correlated with social impairment. Patients with no social impairment showed a heightened neural response to opposite-gender faces after 30s, whereas patients with mild-moderate social impairment failed to ever show a heightened response.
CONCLUSION - Alterations in neural responses during out-group processing predicted degree of social impairment in patients with schizophrenia; thus, neural responses to opposite-gender faces may provide a novel measure for studies of treatment response and disease outcome.
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