Depression, Apathy, Anhedonia, and Fatigue in Parkinson’s Disease

Depression, apathy, anhedonia, and fatigue are common neuropsychiatric symptoms in Parkinson’s disease (PD) and impact deeply on health-related quality of life. The present chapter focuses on their definition, pathophysiology, epidemiology, assessment tools, relationship with other PD nonmotor-associated features, and management. Despite the importance of recognizing these disorders in PD, their diagnosis is greatly complicated since motor or cognitive features of the neurological disorder overlap with them. Furthermore, many features of depression, apathy, anhedonia, and fatigue are imbricated one with each other, further tangling up their assessment.