What is Parkinson's?

M. J. Fox  Parkinson's 101

https://www.michaeljfox.org/parkinsons-101

APDA - Parkinson's disease (PD) is a neurodegenerative disorder that affects predominately dopamine-producing (“dopaminergic”) neurons in a specific area of the brain called substantia nigra.

Symptoms generally develop slowly over years. The progression of symptoms is often a bit different from one person to another due to the diversity of the disease.

https://www.parkinson.org/understanding-parkinsons/what-is-parkinsons