John,

I agree that the map is quite telling. My theory is that for many of us in urban areas the culprit is not pesticides but the air we breathe. A substance referred to as MMT is in our gasoline as a substitute for lead (ironically) and it's main component is Manganese. It is fine particulate matter that we breathe in and that easily passes the blood brain barrier. Now check out the research on Pubmed for the incidence of Parkinsonism in populations near Manganese production factories and in highly polluted areas like Mexico City.
There is actually an article tying MMT to Alpha-Synuclein aggregation with brain damage beginning in childhood! I have written embarrassingly long posts on this if you search the archives.

When I look at that map it further cements the MMT theory for me. Look at the rate of prevalence in the LA region for example vs. the rest of California and the entire Western region. LA is legend for its expressway traffic jams. Though with the population rate, why isn't PD more prevalent? I am guessing the dry air has a lot to do with it. Look at rates for Seattle. Fewer people but moist air. Not exactly scientific, but I am thinking we could easily apply weather phenomenon and scientific methodology to the theory. Does anyone else find this plausible? Any other ideas in looking at the map? I am not sayin it is just MMT but air pollution in general...incidentally my childhood home backed up to an expressway.

This is all keeping in mind the multiple hit theory of sporadic PD...another person may find their environmental trigger is something entirely different if they have one at all since one can acquire the disorder through genetics alone.

Laura