Electrophysiology of Social Reward Processing in Schizophrenia

Abstract

Poor social outcomes have been long observed in schizophrenia. Most studies have identified social cognition as an important contributor to social functioning. Recent research suggests that some people with schizophrenia do not appropriately respond to social rewards, including facial expression of positive affect. The aim of the current study was (1) to use electroencephalogram (EEG) and the event related potential (ERP) technique to examine how people with schizophrenia (SZ) and healthy control (HC) participants anticipate and respond to social (smiles) and nonsocial (money) types of feedback; (2) to examine how deficits in social reward processing are associated with motivation and pleasure deficits and social functioning; and (3) to examine differential contributions of social cognition and social reward processing in understanding functioning. Social and monetary incentive delay tasks were used to characterize reward processing. The stimulus preceding negativity (SPN) was evaluated as an index of reward anticipation, and the reward positivity (RewP) was evaluated as an index of reward sensitivity.

Results indicated that HC participants (n = 22) showed significantly more anticipation of reward feedback than neutral feedback, as indexed by the SPN. SZ participants (n = 25) showed similar anticipation regardless of whether there was a potential to win a reward. SZ participants were more sensitive to social rewards than HC participants, as indexed by a larger RewP. We were unable to measure the RewP on the money task; however, exploratory analyses on a P2 component suggested there were no group differences in nonsocial reward sensitivity. Within the SZ group, reduced social reward anticipation was related to greater motivation and pleasure deficits but not social functioning. Social cognition was not significantly related to social functioning or social reward processing in the SZ sample.

This is the first study to measure the electrophysiological correlates of social and nonsocial reward processing in schizophrenia. Findings provide preliminary evidence of a generalized anticipatory deficit in schizophrenia that is related to impairments in motivation and pleasure. Reward sensitivity to social rewards appears to be intact. Future experimental design considerations are discussed.