2026 ECNP Congress

PS03-3238

Reward processing and delusions in schizophrenia: preliminary fMRI findings within the aberrant salience model

Nuria Ramiro-Sousa — I. París-Gómez, B. Yildirim, A. Urkola Arantzazistroki, P. Del Olmo Encabo, A. Aquino Servín, F. Collazos Sánchez, P. J. McKenna, P. Fuentes-Claramonte, E. Pomarol-Clotet · Fundació Hospitalàries Barcelona, Psychiatry, Barcelona, Spain

2026 ECNP Congress

INTRODUCTION The aberrant salience hypothesis, proposed by Shitij Kapur, suggests that dopaminergic dysregulation in schizophrenia leads to the inappropriate attribution of salience to neutral stimuli, contributing to the formation of delusions [1]. Functional neuroimaging studies using monetary reward paradigms have examined this framework, particularly during reward anticipation and outcome phases. However, findings have been inconsistent: while some meta-analyses report reduced ventral striatal activation during reward anticipation [2], others describe increased activation in striatal and limbic regions during reward outcome [3]. Importantly, the specific relationship between reward processing and delusional symptomatology remains underexplored. This study examines neural correlates of reward anticipation in patients with schizophrenia and current delusions, focusing specifically on delusional symptomatology, using an fMRI-adapted Monetary Incentive Delay (MID) task.

METHODS A modified version of the Monetary Incentive Delay (MID) task was implemented during fMRI, including anticipation and feedback phases, along with dynamic difficulty adjustment based on individual performance to maintain consistent task engagement across participants. Participants were recruited as part of an ongoing study that included patients with schizophrenia (with and without delusions) and healthy controls. Clinical assessment included standardized diagnostic interviews and symptom rating scales, with a specific focus on the presence of current delusions. After excluding participants due to task performance issues or excessive head motion, the current analysis included 16 patients with schizophrenia and current delusions, and 24 healthy controls matched for demographic variables. Patients without delusions were not included in the present analysis due to insufficient sample size. Behavioral measures included reaction times during reward and neutral conditions. fMRI data were analyzed using general linear models, focusing on reward anticipation (reward cue > neutral cue contrast), allowing the identification of brain regions associated with motivational salience processing.

RESULTS Reaction time analysis showed that both groups responded significantly faster in the reward condition than in the neutral condition (p < 0.001), indicating sensitivity to reward contingencies. Patients with delusions were significantly slower than controls in both the reward condition (p = 0.0017) and the neutral condition (p = 0.0002), reflecting reduced overall response speed.Both groups showed activation in regions of the reward circuit during the anticipation phase, including the caudate nucleus and putamen, with more extensive activation in the control group. These findings are consistent with engagement of reward-related striatal regions during reward anticipation in both groups. No significant differences were found between patients with delusions and healthy controls.

CONCLUSION The Monetary Incentive Delay (MID) task captures reward anticipation processes in both groups, showing activation in striatal regions. However, with the current sample size, no significant differences were detected between patients with delusions and healthy controls. Larger samples are needed to determine whether subtle group differences in reward processing can be detected. The inclusion of patients without delusions will contribute to elucidate the specific association between reward processing and this symptom.

References

  1. Kapur S. Psychosis as a state of aberrant salience: a framework linking biology, phenomenology, and pharmacology in schizophrenia. Am J Psychiatry. 2003;160:13–23.
  2. Radua J, Schmidt A, Borgwardt S, Heinz A, Schlagenhauf F, McGuire P, et al. Ventral striatal activation during reward processing in psychosis: a meta-analysis of fMRI studies. JAMA Psychiatry. 2015;72:1243–1251.
  3. Zeng J, Yan J, Cao H, Su Y, Song Y, Luo Y, et al. Neural substrates of reward anticipation and outcome in schizophrenia: a meta-analysis of fMRI findings in the monetary incentive delay task. Transl Psychiatry. 2022;12:448.