Is fatigue associated with cognitive dysfunction in early Parkinson's disease?

Introduction: Fatigue is a common and disabling symptom which may be seen in early Parkinson's disease (PD). Our understanding of the phenomenology and etiology of fatigue in PD is limited. The objective of this study was to determine whether fatigue was related to cognition in early PD patients. Methods: The study is part of the Norwegian ParkWest project, a population-based cohort study, comprising 184 de novo, drug-naive patients with PD. PD was diagnosed according to the Gelb criteria. Fatigue was assessed by the Fatigue Severity Scale (FSS). Cognition was assessed by a battery of tests evaluating functions in the domains of verbal memory, processing speed, executive function and visuospatial abilities. Results: 107 of the cohort had moderate to severe fatigue (FSS >= 4). In univariate correlation analyses high fatigue score was correlated to disease severity, presence of sleep problems, depressive symptoms, apathy, reduced processing speed and reduced visuospatial abilities. In a multiple regression analysis only disease severity (measured by the UPDRS part 3), sleep problems, depressive symptoms and reduced visuospatial abilities contributed to the model. Conclusion: Fatigue is associated with visuospatial function in early PD patients. Further studies are needed to determine the pathophysiologic relevance of this association. (C) 2017 Elsevier Ltd. All rights reserved.