Several cups of black tea later.........
Yes, Turnip, there may be 2 phases to the disease, an initial conversion event and then a self propagating progression. A plausible sequence of events which is being shown experimentally is:
the transformation of alpha synuclein protein into a toxic form in the splanchnic nerve of the gut (no experimental evidence yet);
migration of the toxic alpha synuclein initially to the brain stem (experimental evidence);
propagation of toxic alpha synuclein in a progressive manner from the brain stem to several regions of the brain (experimental evidence). Experiment and neuroanatomical studies have shown that toxic alpha synuclein protein behaves like a prion (an agent of infection);
Once in the neuron the toxic form of alpha synuclein causes natural alpha synuclein present to convert to the more toxic form.(Experimental evidence)
The neuron's rubbish disposal systems cannot cope with the sudden build up of toxic protein and the cell dies.(experimental evidence?)
The toxic prion disrupts cellular membranes either by sitting in them or by switching off production of their components. Inability to make energy and maintain cell internal environment ensues and the cell dies. (experimental evidence)
Theaflavins have been shown to interfere with the transformation of natural alpha synuclein into other forms ans also to stimulate autophagy (rubbish disposal). So they could in theory be acting at the initial conversion event in the gut or on the progressing disease in the brain. However I suspect the concentration of thiaflavins achieved in the gut by a cup of black tea is more biologically relevant than that achieved in the brain. It would be interesting to see the effect of theaflavins (at the level found in the CSF) on infected neuronal cell systems like those used by Desplats et al. to test the possibile effects on cell death. (http://www.pnas.org/content/106/31/13010.full
So yes, on reflection my gut feeling is tea is probably preventing the initial disease event..............
Thanks Claire for the info on other agents that affect Parkinson's symptons.