New methods to assess the correlation between reward system and chronic fatigue in patients on chronic hemodialysis

Background: One of the most frequently observed clinical manifestation in patients with kidney disease on chronic hemodialysis (HD) treatment is fatigue, a complex symptom that deeply affects their quality of life [1]. Research suggested that fatigue is associated to chronic inflammation and disfunction of the basal ganglia, leading to an alteration of reward processes, in chronic patients [2]. Recently, there is a growing interest in finding new methods and perspectives to assess these dimensions in chronic populations. For this reason, this study aimed to examine the correlation between fatigue and motivational systems in HD patients. Materials and methods: To assess the effect of fatigue on motivational and physical aspects, the Fatigue Severity Scale (FSS) was applied to a total of ninety-four hemodialysis patients. While the Behavioural Activation System (BAS) and Behavioural Inhibition System (BIS) Scale was administered to measure their mechanisms of reward, that predispose to activation or inhibition of action. Finally, State-Trait Anxiety Inventory (STAI-Y) and Beck Depression Inventory (BDI-II) were used to detect the presence of anxiety and depression. Results: FSS score was significantly higher in patients with high BIS Z-score than in patients with low and medium BIS Z-score. Conversely, all BIS Z-score groups of patients showed similar BDI and STAI-Y1/Y2 scores. Finally, the correlation between BIS and FSS score was found to be significant. Conclusions: Globally, these findings suggest a correlation between fatigue symptoms and the behavioral inhibition system that, within the motivational mechanisms, is related to the inhibition of action with possible consequences on patients’ engagement. References 1. Bossola M, Di Stasio E, Antocicco M, Panico L, Pepe G, Tazza L. Fatigue is associated with increased risk of mortality in patients on chronic hemodialysis. Nephron. 2015; 130:113–118. 2. Bossola M, Di Stasio E, Giungi S, Rosa F, Tazza L. Fatigue Is Associated With Serum Interleukin-6 Levels and Symptoms of Depression in Patients on Chronic Hemodialysis. J Pain Symptom Manage. 2015;49:578–85.