Parkinson’s Disease (PD) is a brain disorder that leads to shaking, stiffness, and difficulty with walking, balance, and coordination. It is also the second most common neurodegenerative disease after Alzheimer’s disease. Population prevalence of PD increases from about 1% at age 60 to 4% by age 80.
The main pathological characteristics of PD are dopaminergic cell death in the brain's basal ganglia. There is no cure for PD now. However, medicines, surgical treatment, and other therapies can often relieve some symptoms.
Levodopa or l-dopa is the most common and most effective treatment of PD for many decades, however for long-term treatment, it also causes Levodopa-induced dyskinesia (LID).
PD has a death rate of 1.81% and resulted in about 211,000 deaths globally in 2016. The annual cost per affected person in the U.S. is around $10,000 and the total being around $23 billion.
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 NIH page of PD
 Pandey, Sanjay, and Prachaya Srivanitchapoom. “Levodopa-induced Dyskinesia: Clinical Features, Pathophysiology, and Medical Management.” Annals of Indian Academy of Neurology vol. 20,3 (2017): 190-198.
 Findley LJ "The economic impact of Parkinson's disease". Parkinsonism & Related Disorders. 13 Suppl (Suppl): S8–12.
 Feigin VL, et al.. "Global, regional, and national burden of neurological disorders, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016". Lancet Neurol. 18 (5): 459–80.