Moondaughter, thanks for raising the issue of altitude. I'm looking into it.

My thanks go to GerryW for pointing out the paper by Qin et al. [1]. They write:

"LPS reduced the number of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra (SN) by 23% at 7-months post-treatment, which progressed to 47% at 10 months.Together, these data demonstrate that through TNFalpha, peripheral inflammation in adult animals can: (1) activate brain microglia to produce chronically elevated pro-inflammatory factors; (2) induce delayed and progressive loss of DA neurons in the SN. These findings provide valuable insight into the potential pathogenesis and self-propelling nature of Parkinson's disease."

The key word here is "self-propelling". I take this to mean that a single environmental hit can set off an immune system response that cannot be stopped purely by ensuring there are no more environmental hits. So, if this is true of your type of PD, moving - even to the perfect location - will not, in itself, stop progression.

But can moving slow progression?

This will depend on whether new toxins add to the rate at which damage is done. Does anyone have any information on this?

[1] "Systemic LPS causes chronic neuroinflammation and progressive neurodegeneration."
Qin L, Wu X, Block ML, Liu Y, Breese GR, Hong JS, Knapp DJ, Crews FT
Glia. 2007 Apr;55(5):453-62.
http://www.ncbi.nlm.nih.gov/pubmed/17203472

John