Parkinson's disease is a chronic, degenerative neurological disorder
that affects one in hundred people above age sixty. While the average age at
onset is sixty, people have been diagnosed at age 18. There is no objective
test for disease, so the rate of misdiagnosis can be relatively more,
especially when the diagnosis is made by a non-specialist. Estimates of the
number of people living with the disease therefore vary, but recent research
indicates that at least one million people in the United States, and more than
five million around world, have Parkinson's disease.