Effort allocation for rewards in first-episode psychosis and first-episode mania

Background: Effort-based decision-making has been shown to be impaired inpatients with schizophrenia. Motivational deficits can also be seen in bipolardisorder given the growing evidence of phenomenological, biological, and genetic overlaps between schizophrenia spectrum disorders and bipolar disorder.This study aimed to evaluate the effort for reward in subjects who had the firstepisode of psychosis (FEP), the variation of this effort according to the size andprobability of reward; and to compare the changes in the effort for the rewards inpatients with the first episode of mania (FEM), and healthy control groups. Wealso aimed to assess whether these deficits in the willingness to expend effort forrewards are related to negative symptoms, positive symptoms, thought disorder,global cognition, and medication.Methods: In this study, effort-based decision-making was compared in patientswith the FEP (n¼53), the FEM (n¼45), and the healthy controls (n¼37). Effortbased decision-making has been evaluated using Effort-Expenditure for RewardsTask( EEfRT). This test evaluates individuals' efforts based on reward magnitudeand probability. Global cognition scores were calculated by a factor analysisbased on a comprehensive neurocognitive battery. Negative symptoms wereassessed with the Brief Negative Symptom Scale (BNSS). Positive symptoms wereevaluated with the Scale for the Assessment of Positive Symptoms (SAPS).Chlorpromazine equivalent doses were calculated for people having medicaltreatment.For EEfRT, the data were analyzed using a mixed model repeated measuresANOVA with the group as a between-subject factor and both probability andreward level (low, medium, high) as within-subjects factors.Results: The main effect for interaction between probability, reward, and thegroup was significant in EEfRT (F¼4,546 p&lt;0,001). Post hoc tests for therepeated measures ANOVA showed significant differences between patients withFEP and healthy controls, and between patients with FEM and healthy controls.In terms of the likelihood of hard task choices, conditions that differed betweengroups were medium probability-low reward (F¼6,02, p¼0,003), mediumprobability- high reward (F¼11,52, P&lt;0,001), high probability-medium reward(F¼15,01, p&lt;0,001), and high probability-high reward (F¼46,78, P&lt;0,001).Global cognition was associated with reduced effort only in high rewardmagnitude and high probability status in patients with FEP. The likelihood ofchoosing the hard task wasn’t correlated with medication, positive symptoms,negative symptoms, or thought disorder in patients with FEP and FEM. Inaddition, a significant difference was found between patients with FEP and FEMin uncorrected analysis in the high reward-high probability condition (p¼0,009).Conclusions: Deficits in the willingness to expend effort for rewards wereevident in FEP and FEM. Demonstration of motivational deficits in the sameprobability and reward situations in both groups may indicate a common pathophysiological mechanism in some subgroups of these disorders. The currentstudy reported cross-sectional evidence for decision-making abnormalities inschizophrenia and bipolar disorder. Further comparative research investigatinglongitudinal changes in effort-based decision-making in the early phases of bipolar and psychotic disorders is needed.</p