Predictors of fatigue severity in early, de novo Parkinson disease patients: A 1-year longitudinal study

Introduction: Fatigue is one of the most common and disabling nonmotor symptom in Parkinson's disease (PD). The aim of the present study was to investigate the 1-year course of fatigue in a consecutive sample of de novo drug-naive patients with PD, and at systematically searching for baseline motor and nonmotor predictors associated with fatigue severity over time. Methods: Fifty-five consecutive de novo PD patients (age: 64.71 +/- 7.74 years) underwent a comprehensive examination, including Parkinson Fatigue Scale, Epworth Sleepiness Scale, Parkinson's Disease Sleep Scale, Beck Depression Inventory, Parkinson's Anxiety Scale, Apathy Evaluation Scale, and an extensive neuropsychological evaluation. Bivariate and multiple regression analyses were performed to identify baseline predictors independently related to fatigue severity at 1-year follow-up. Results: Prevalence rate of fatigue (defined by PFS cut-off) increased from 22% at baseline to 38% at 1-year follow-up. A similar increase in prevalence was observed for excessive daytime sleepiness, and apathy. Among patients with fatigue at baseline, 91% had fatigue at follow-up too (i.e., persistent fatigue). Multivariate regression analysis identified fatigue (p < 0.01), daytime sleepiness (p < 0.01), and emotional apathy (p < 0.01) as the main baseline variables significantly predicting fatigue severity at 1-year follow-up. Conclusion: In early PD, fatigue increases and persists over time, and its severity is related to higher baseline levels of fatigue, excessive daytime sleepiness, and emotional apathy. These results warrant to monitor fatigue since the early stage of disease, and suggest that treating excessive daytime sleepiness and emotional apathy might prevent its worsening.