One of the hallmarks of PD is the clumps in neurons called Lewy bodies. These are glycation products formed when sugars and proteins interact. They belong to a family of similar (maybe even identical) clumps with other names, usually that of the guy who first described them.

Lewy was the guy that described them in PD, thus the name. The ONLY thing that definitively says that you had PD is if there are Lewy bodies in your SN once you are dead. That's the "gold standard." So lewy bodies are important.

Anne Frobert, who occasionally posts here, turned me on to the work of a researcher named Braak. He discovered that Lewy bodies are, indeed, found in the SN but he also discovered that they showed up there last. First, they showed up in the wall of the stomach. Then they followed a path up the vagal nerve to the brainstem and through the brain centers one by one and finally to the SN.

Think of the lewy bodies as footprints on the beach. The first one represents the stomach and the others form a string through both time and space toward the SN. But the first footprint is the one before you.

PD doesn't start in the SN. It doesn't even begin in the brain. It starts in the stomach wall and creeps up the nerve pathways and eventually ends up in the SN.

It could be a virus, a bacterium, or a toxin. Or a combination.

We know that a virus can live in the nerve fibers and follow them to cause shingles, for example. We know that several viruses cause clumps similar to Lewy bodies, too.

Yes, I think this story is very interesting.