Is there a definite answer as to whether we should take B12 or not being mercury posioned?

I've read in sweden they use b12 in mercury toxic patients and they have remarkable results. I'd need an answer on b12 as my brain is shutting down and I think I already have mental ilness and wonder if it would help with brain function.

can smeone say if it helps their brain?

and there's also the question what b12 to take - the cyanocobalamine one or the methyl-cobamine (that can mehylate mercury)??

please answer!!