Rick,

Thank you for your reply.

(What happened to the book?)

The key issue that you raise seems to me to be whether PD "started" in or about 1800. If I understand you correctly, you would argue in favour of this because, although tremors had been noted before, the combination of slowness, tremor and stiffness had not been.

A blogger [1] gives a number of examples from ancient civilizations of what may have been incidences of PD. He points out that:
"The Ayurveda’s description of kampavata includes tremors, stiffness, depression and a depletion of movement. The Ancient Indians prescribed a number of drugs to battle the symptoms of the disease, some of which scientists have come back to review today. These include the root of Withania somifera, the seed of Mucuna Pruriens Bak, Root of Sida Cordifolia and the fruit of Hyocyamus reticulatus".

I find this evidence compelling. So, I don't think that PD was new in 1800.

However, I hope you are right, because if we have a start date, this limits the number of pathogens that could be responsible for PD. London, and other cities were polluted before the Industrial Revoltion. So, I don't think that we should look for pollution in general as the culprit, but for something in particular that was added to the environment then. For example, a bit late, but aluminium was first isolated in 1827; there was an influenza epidemic in England in 1775-1776 [2].

The Industrial Revolution didn't happen in a day, there was a roll out of technologies and a move to urbanization that happened in different places at different times. If this is the case, we should see the same trends that happened in London around 1800 happen in other places later, indeed up to the present day.

References

[1] http://graecomuse.wordpress.com/2012...cient-history/

[2] http://en.wikipedia.org/wiki/List_of_epidemics

John