Parkinson Disease Epidemiology, Pathology, Genetics, and Pathophysiology.

Parkinson disease is a complex, age-related, neurodegenerative disease associated with dopamine deficiency and both motor and nonmotor deficits. Many environmental and genetic factors influence Parkinson disease risk, with different factors predominating in different patients. These factors converge on specific pathways, including mitochondrial dysfunction, oxidative stress, protein aggregation, impaired autophagy, and neuroinflammation. Ultimately, treatment of Parkinson disease may focus on targeted therapies for pathophysiologically defined subtypes of Parkinson disease patients.