Zinc levels in Parkinson's patients much lower than healthy controls:

Association Between Serum Zinc Levels and the Risk of Parkinson's Disease: a Meta-Analysis. - PubMed - NCBI

A broader discussion of serum metal levels in PD can be found in a thread from 2012:

Serum metal levels

To quote from that thread:

Ahmed and Santosh [1] measured the serum levels of various metals in PD (n=45) and non-PD (n=42) people in South India.

They found that "Al [high in PwP], Cu [high], Fe [low], Mn [high] and Zn [low] were dominantly reponsible for the separation of PD from normal".

They went on to look at the correlation between metal ratios and PD: "Al/Cu, Al/Fe, Al/Mn, Al/Zn, Cu/Fe, Cu/Zn, Fe/Zn and Mn/Zn were increased and Fe/Mn and Cu/Mn were decreased in PD compared to healthy control".

They describe a neural network (a computing technique, ironically inspired by the working of the brain) which, taking together all the relationships, gives a 95% diagnostic accuracy. (But, note the small sample size.)

Reference

[1] Ahmed SSSJ, Santosh W (2010) Metallomic Profiling and Linkage Map Analysis of Early Parkinson's Disease: A New Insight to Aluminum Marker for the Possible Diagnosis. PLoS ONE 5(6): e11252. doi:10.1371/journal.pone.0011252
400 Bad Request

John

I think that this is interesting.

It has been known for some time that α-synuclein can bind a range of metal ions. It has been argued that this may lead to production of Reactive Oxygen Species (ROS) which may lead to neuronal damage in people with PD; this is a recent, somewhat technical, paper about this Alpha-Synuclein Oligomers Interact with Metal Ions to Induce Oxidative Stress and Neuronal Death in Parkinson's Disease.

It is possible (though speculative) that the low levels of Zn2+ in people with PD may allow α-synuclein to preferentially interact with redox-active metal ions like Fe3+ and Cu2+, leading to generation of ROS.

I've not done one of these geographical associations for some time. I find them useful not so much as proof, which of course they aren't - there is no rigorous statistical analysis, nor does it take into account any of a myriad of confounding issues - but to kick-out obviously flawed hypotheses.

Compare:
A. The geographical prevalence of PD in the US [1].
B. Zinc in the soil in the US [2].

Eye-balling the maps I suspect that there is a small negative association between the two. Thus, we can't throw out the hypothesis that low levels of zinc are linked to PD.

I would suspect that the causal mechanism by which zinc levels in the body associate with those in the soil is through the food chain and the water supply.

References:

[1] "Geographic and Ethnic Variation in Parkinson Disease: A Population-Based Study of US Medicare Beneficiaries"
Allison Wright Willis,a,* Bradley A. Evanoff,b Min Lian,b Susan R. Criswell,a and Brad A. Racette
Geographic and Ethnic Variation in Parkinson Disease: A Population-Based Study of US Medicare Beneficiaries
Figure 1.

[2] "Element Concentrations in Soils and Other Surficial Materials of the Conterminous United States"
US Geological Survey
https://pubs.usgs.gov/pp/1270/pdf/PP1270_508.pdf
Original page 102

John

Interesting points. There is an antagonistic relationship between copper and zinc. In fact, many homes have water pipes that are made from copper.