I don't think we can ignore the records in ancient India given they have proven Ayurvedic treatment going back thousands of years. If you think of it (sobering as it is) we really are no further ahead given that we all are diagnosed on presenting symptoms, clinical observation, and response to treatment, so we cannot dismiss any account of PD on this basis.

There is a compelling logic to associating PD with the rise of industrial pollution, but Parkinson gives us only 6 case studies. We would need to know if these people lived or worked in and near factories. Charcot really is the one who put PD on the map with extensive studies beginning in 1861 that spanned 20 years. He and his students defined the cardinal signs; it would be fantastic if they collected patient data. The Industrial Revolution coincides with the birth of neurology and PD was just being defined as a bona fide disorder, so we cannot tell if there was an increase in incidence based on pollution or just that it was now being recognized more by doctors as a disease?

If we acknowledge Ayuraveda, there is some merit that PD was around in ancient times. This actually lends support to Rick's theory. It is easy to name a neurotoxin that bridges ancient to modern PD and likely connects much (if not all) neurodegenerative disease: that is chronic exposure to airborne metals. Early metallurgy (PD 2500 BC) evolves to pollution from smelting (19th c.) to addition of lead followed by Manganese to automobile fuel (20th century). Someone just needs to connect the dots... (not forgetting pesticides, but Round Up was a mere gleam in the early Industrialist's eye.)

I am thinking similar stats pop up across the world.

Fine-Particulate Air Pollution and Life Expectancy in the United States. NEJM 2009