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160. Dissociation between rational mistrust and spite sensitivity in psychosis patients on the Minnesota Trust Game during fMRI
Psychosis patients frequently experience delusions that are persecutory in nature, yet it is difficult to measure behaviorally. We utilized behavioral economics principles in a two-stage economic game to identify persecutory decision-making. 44 patients with early psychosis completed the Minnesota Trust Game in a 3T scanner. In the first stage, the player decides whether to take a safe lower payout ($10) or to allow their partner to choose between an equal payout for both players ($20 each) or an alternate payout that parametrically varied the amount the player would receive (losing $15 to winning $20). The alternate payout had two conditions: The $25 condition could lead to “rational mistrust”, where the partner could get more money at a cost to the player. In contrast, for the $15 condition the player would only mistrust the partner if they were concerned about the partner’s spitefulness, an operationalization of suspiciousness. We identified a dissociation of neural regions across condition and risk, in which low risk during rational mistrust activated bilateral caudate nuclei (associated with anticipated reward), while high risk in the spite sensitivity condition was associated with greater activation in social cognition and reward regions: the medial PFC, bilateral lateral OFC, and PCC.