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

Uzman Özbek S., Gürbüz M., Çesim E., Demir M., Yalınçetin B., Ermiş Ç., ...More

Neuroscience Applied, vol.2, pp.35, 2023 (Peer-Reviewed Journal)


Background: Effort-based decision-making has been shown to be impaired in patients with schizophrenia. Motivational deficits can also be seen in bipolar disorder 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 first episode of psychosis (FEP), the variation of this effort according to the size and probability of reward; and to compare the changes in the effort for the rewards in patients with the first episode of mania (FEM), and healthy control groups. We also aimed to assess whether these deficits in the willingness to expend effort for rewards are related to negative symptoms, positive symptoms, thought disorder, global cognition, and medication. Methods: In this study, effort-based decision-making was compared in patients with the FEP (n¼53), the FEM (n¼45), and the healthy controls (n¼37). Effortbased decision-making has been evaluated using Effort-Expenditure for Rewards Task( EEfRT). This test evaluates individuals' efforts based on reward magnitude and probability. Global cognition scores were calculated by a factor analysis based on a comprehensive neurocognitive battery. Negative symptoms were assessed with the Brief Negative Symptom Scale (BNSS). Positive symptoms were evaluated with the Scale for the Assessment of Positive Symptoms (SAPS). Chlorpromazine equivalent doses were calculated for people having medical treatment. For EEfRT, the data were analyzed using a mixed model repeated measures ANOVA with the group as a between-subject factor and both probability and reward level (low, medium, high) as within-subjects factors. Results: The main effect for interaction between probability, reward, and the group was significant in EEfRT (F¼4,546 p<0,001). Post hoc tests for the repeated measures ANOVA showed significant differences between patients with FEP and healthy controls, and between patients with FEM and healthy controls. In terms of the likelihood of hard task choices, conditions that differed between groups were medium probability-low reward (F¼6,02, p¼0,003), medium probability- high reward (F¼11,52, P<0,001), high probability-medium reward (F¼15,01, p<0,001), and high probability-high reward (F¼46,78, P<0,001). Global cognition was associated with reduced effort only in high reward magnitude and high probability status in patients with FEP. The likelihood of choosing the hard task wasn’t correlated with medication, positive symptoms, negative symptoms, or thought disorder in patients with FEP and FEM. In addition, a significant difference was found between patients with FEP and FEM in uncorrected analysis in the high reward-high probability condition (p¼0,009). Conclusions: Deficits in the willingness to expend effort for rewards were evident in FEP and FEM. Demonstration of motivational deficits in the same probability and reward situations in both groups may indicate a common pathophysiological mechanism in some subgroups of these disorders. The current study reported cross-sectional evidence for decision-making abnormalities in schizophrenia and bipolar disorder. Further comparative research investigating longitudinal changes in effort-based decision-making in the early phases of bipolar and psychotic disorders is needed.