Yeah, mercury doesn't play nice in the brain. Mercury was the fuse that lit my methylation bomb. I could go on and on when it comes to what mercury/methylation has done to me. It is my contention that people with CFS are even at higher risk because almost all of us will have CCSVI to one degree or another. Bear with me if I tell you something that you already know...
ME/CFS is a mitochondrial problem. It weakens the cells in the heart and blood regurgitates through the tricuspid valve and back up the jugulars. This may (or may not) be different from CCSVI that is found in 54% of those with MS. We may not need to have our veins opened, I'm thinking. We need to restore cellular health and the tricuspid valve might smarten-up. This is important because with blood pushing against the blood-brain-barrier, we end up with venous congestion, poorer oxygen perfusion, less ability to remove toxic by-products (as in more brain-fog) AND the pressure could make the BBB more permeable to mercury.
So not only is our (as in us under-methylators) detox system messed up to where we might start hoarding mercury but we put pressure on the BBB to get more into the brain....sheesh!
In terms of the chelators that you listed, only ALA has the double thiol group necessary to latch onto mercury. B vitamins can boost our own detox system, but still who has 15 years to half their brain load? NAC in rat studies increased brain loading of mercury as opposed to decreasing. But to be fair, our BBB is more sophisticated and we have to take care in how we apply data like this. I think with its single-thiol group that NAC by itself will not get the job done but am open-minded to consider anything that states otherwise. BTW, greetings from the Great White North, I'm from Powassan Ontario...near North Bay. brad