Amalgam Illness says that a lack of adequate B-12 is a big cause of deranged brain metabolism. It is involved in all kinds of methylation reactions. While there are many mercury toxic people who can't take B12, I am one of them that it helps.I do take the methylated form. It has been used by some on the autism forums with success. Having said that, it is an individual thing. Some people are not helped by B-12 and some respond poorly to it. That's just what I have come up with on doing research on the vitamin, because I have been found to have a B12 deficiency in the past.

Hope this helps a bit.