Exploring Fatigue in Parkinson's Disease: A Comprehensive Literature Review.

Fatigue is one of the most prevalent and debilitating non-motor symptoms of Parkinson's disease (PD), affecting up to two-thirds of patients and significantly impacting quality of life. This review provides a comprehensive analysis of its complex pathophysiology, prevalence, clinical presentation, assessment methods, and current management strategies. Fatigue in PD is linked to dysfunction in dopaminergic and non-dopaminergic pathways, neuroinflammation, genetic predispositions, and metabolic dysregulation. Reported prevalence rates range from 36% to 60%, highlighting the need for standardized assessment tools and a universally accepted definition. Clinically, fatigue is characterized by an overwhelming and abnormal sense of exhaustion, often preceding motor symptoms by years. Distinguishing it from sleepiness, apathy, and depression is crucial for accurate diagnosis and treatment. Assessment primarily relies on patient-reported scales, such as the Fatigue Severity Scale and the Parkinson's Disease Fatigue Scale. Management includes both pharmacological and non-pharmacological approaches, with medications like methylphenidate and rasagiline showing potential, alongside physical exercise, cognitive behavioral therapy, and sleep disorder management. Further research is essential to unravel the underlying mechanisms, identify objective biomarkers, and develop more effective, targeted treatments for this burdensome symptom.