Fatigue in Parkinson's Disease.

Fatigue is a common symptom in Parkinson's disease (PD), affecting approximately half of all patients. Fatigue is a significant contributor to reduction in quality of life and is a leading cause of disability. Despite the clear impact of fatigue on persons living with PD, research progress has been slow in this area in terms of uncovering the mechanisms of fatigue and there are currently no evidence-based treatments. Although fatigue is often viewed as a subjective and nonspecific symptom which cannot be studied rigorously, there is an emerging science of fatigue which is based on a careful and precise taxonomy of the construct of fatigue. In this chapter we will review advances in our conceptualization of fatigue, including providing definitions useful for both research and clinical care. We will then provide an overview for an approach to the assessment and management of persons with PD who complain of problematic fatigue. We will conclude by reviewing methods for clinical research, including outcome measures for clinical trials, findings from recent mechanistic studies, and suggestions for future research.