Background

Studying young adults in the subclinical phase of psychotic disorder could provide information on the development of psychosis and contribute to early interventions. Previous research in patients with psychotic disorder shows alterations in the brain’s reward system (ventral medial prefrontal cortex (VMPFC), ventral striatum (VS), nucleus accumbens, 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 for the subclinical psychotic experiences (PE) group that reward anticipation is reduced.

Material & methods

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 determined 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 or loss levels (small; €0.10, medium; €0.60 and large €3.00). During the anticipation phase functional brain activation was recorded. fMRI analysis were performed using FSL with a focus on the reward versus neutral contrasts. In FSL a GLM was applied to the data with regressors for each condition. Next to whole brain analysis a region of interest (ROI) analysis on the VMPFC, VS and VTA was conducted. After extracting data, further processing and statistical analysis was performed by regression analysis in STATA.

Results

Mean age, gender and educational level did not differ between groups On average participants were 22 years old, with slightly more females in the HC-group compared to the PE-group. Trend significance for slower reaction times towards the loss cue in the PE-group was found. No significant differences in cue reaction times, non responses and money gain were found comparing both groups. 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 win outcome > neutral increased activation was found in the left temporal pole. This finding was confirmed on the contrast combining the three win levels > neutral. ROI analysis did not find significant differences between groups.

Discussion and conclusion

The difference in reaction time towards the square cue could indicate a difference in loss-avoidance in the PE group. Therefore, partly altered reward anticipation in individuals with subclinical psychosis may indicate that underlying dopamine dysregulation may be more subtle in this phase, thereby not (yet) influencing this behavioral mechanism. Interestingly, increased activation was found in the PE-group compared to the HC-group in the reward anticipation contrast. This might point to a compensatory mechanism in the prodromal phase.

Acknowledgements

No acknowledgement found.

References

No reference found.