148. Reward Anticipation in Early Expression of Psychotic Disorder: A Functional MRI Approach

Abstract

Background: Studying young adults in the prodromal phase of psychotic disorder could provide information on the development of psychosis and contribute to early interventions. Previous research in patients with psy-chotic disorder shows alterations in the brain's reward system (ventral medial prefrontal cortex (VMPFC), ventral striatum (VS), nucleus accum-bens, caudate, putamen, ventral tegmental area (VTA)) using the monetary incentive delay task (MIDt). Reward anticipation is the expectation of reward and therefore a positive reinforcement of an action. It is hypothesized in a prodromal psychotic experiences (PE) group that reward anticipation is reduced. Method(s): A sample (n = 25) of young adults aged 16-26 years in the PE-group (CAPE positive distress subscale >= 2) and healthy control (HC) group (n = 42) were analyzed. Reward anticipation was based on reaction times on seven different cues in the MIDt and fMRI was measured during this phase. Cues related to win, loss, or neutral conditions with three gain/loss levels (small; 0.10, medium; 0.60 and large 3.00). During the anticipation phase, functional brain activation was recorded. Whole-brain fMRI analysis was performed using FSL focusing on the reward versus neutral contrasts. A region of interest (ROI) analysis on VMPFC, VS and VTA was conducted. Result(s): Mean age (22 years), gender, and educational level did not differ. Trend signifcance for slower reaction times toward the loss cue in the PE-group was found. No signifcant differences in cue reaction times, non-responses and money gain were found. In the fMRI analysis, main effects of large win (3.00) > neutral were found in both groups showing widespread brain activation. When comparing PE > HC group on the large gain outcome > neutral increased activation was found in the left temporal pole. This fnding was confrmed on the contrast combining all gain levels > neutral. ROI analysis did not fnd signifcant differences between groups. Conclusion(s): The difference in reaction time towards the square cue could indicate a difference in loss avoidance in the PE group. Therefore, altered reward anticipation in individuals with prodromal psychosis may indicate that underlying dopamine dysregulation may be more subtle in this phase, thereby not (yet) infuencing behavioral mechanisms. Increased activation in the PE-group compared to the HC-group in the reward anticipation contrast might point to a compensatory mechanism in the prodromal phase.