Parkinson’s disease (PD) is the second most common neurodegenerative disease after Alzheimer’s disease. An estimated 10 million people have Parkinson’s disease worldwide. (Refer to the World Health Organization page on Parkinson’s disease). The major risk factor for PD is age and incidence rises steeply with aging. Nonetheless, unlike AD, which very rarely afflicts people under age 60, PD strikes people in their 20s, 30s, and 40s who struggle to work and raise families. The estimated global costs of care for PD are > 52 billion per year.

In PD, a protein called α-synuclein forms toxic aggregates, which kill the nerve cells that produce dopamine and other nerve cells in multiple areas of the brain. Aggregated α-synuclein is found in hallmark lesions called Lewy bodies and Lewy neurites in the brain of people who have Parkinson’s disease.

Refer also to Familial Parkinson’s Disease.