Parkinson's disease is a disease of some particular cells (dopaminergic neurones) in a small part of the brain (the substantia nigra) which help in making voluntary movements. It causes slowness of movement, rigidity and tremors. It usually starts between ages 60 and 70 years, can be helped by treatment but is usually gradually progressive, with increasing slowness and difficulty with movement. Death can be due to lung infection (pneumonia) or due to dementia.
Parkinson's disease caused 0.17% of all deaths worldwide in 2002, an average of 16 deaths per million people per year.