ONE-YEAR FOLLOW-UP OF EFFORT-BASED DECISION-MAKING PERFORMANCE IN FIRST-EPISODE PSYCHOSIS PATIENTS

Abstract

Background: Effort-based decision-making has been proposed as a potential mechanism contributing to motivational deficits (amotivation) in psychotic disorder. Previous research has demonstrated altered effort allocation in chronic schizophrenia but produced mixed results regarding its relationship with amotivation. Our recent investigation of effort-based decision-making in first-episode psychosis (FEP) patients has revealed that reduced willingness to expend physical effort for high-value/high-probability reward was most pronounced in clinically-stabilized FEP patients with high levels of amotivation (High-AMO), relative to those with low levels of amotivation (Low-AMO) and healthy controls. This study aims to report preliminary results of effort-based decision-making performance of FEP patients at 1-year follow-up. Methods: The initial study cohort included 45 FEP (based on DSM-IV criteria) patients and 45 demographically-matched controls. Our preliminary findings were based on 34 FEP patients who had completed 1-year follow-up effort-task assessment. Baseline effort-task performance of controls was used for comparison. Effort-based decision-making performance was evaluated using Effort-Expenditure for Reward Task (EEfRT), which measured the degree of willingness to expend physical effort for monetary reward at varying magnitude (low, medium or high) and probability levels (12%, 50% or 88%). Patients were further classified into High-AMO (n=17) and Low-AMO (n=17) groups based on median-split of SANS total score. Comparison analyses among three subject groups (including controls) on effort allocation task performance were conducted. Results: There was no group difference in gender, age and educational level. Repeated-measures analysis of variance (ANOVA) revealed significant main effects of probability (F1.80,136.4=82.9, p<0.001), reward (F2,152=70.7, p<0.001), and probability x group (F3.59,136.4=2.6, p=0.042), and probability x reward (F3.89,295.47=11.1, p<0.001) interactions. Post-hoc contrasts showed that High-AMO group chose significantly fewer high-effort trials at 88% probability condition than controls (t= 2.5, p=0.014), as well as fewer high-effort trials at condition with high-reward at 88% probability level than both Low-AMO group (t= 2.2, p=0.036) and controls (t=4.2, p<0.001), while the latter two groups did not differ from each other. Correlational analyses showed no significant associations of effort-related measures with SANS ratings as well as other symptom dimension scores. Discussion: Our preliminary findings suggest that FEP patients with high amotivation still exhibit aberrant physical effort-based decision-making with reduced willingness to expend effort for high-value/high-probability reward at 1-year follow-up. Analysis of our data upon completion of follow-up assessment of our FEP sample will help further clarify the pattern of effort-based decision-making impairment and its relationship with amotivation 1 year after baseline effort-task evaluation.