Brain fog and dementia are both known to be associated with mercury, so removing amalgams may help. It made all the different in my life:

http://herballure.com/mms

Using a sauna before mercury amalgams have been removed is generally considered a good idea.

Yes, red tattoos may contain mercury and can cause mercury symptoms. I'm not sure if there is a safe removal process for these kinds of tattoos, but I would certain research it to find out. You want to minimize your exposure to mercury as much as possible.

Hope this helps.