Re: psychosis...does seroquel work well with niacin?

"Niacin" is the wrong form of the substance he should take. It's "niacinamide", or even better, "Nicotinamide adenine dinucleotide" (NAD). This in combination with Vitamin C, B6, etc, usually in mega-dose amounts (2000mg+)

Rather than experimenting on your own, especially because of the severity, I suggest you try to get him to an ORTHOMOLECULAR psychiatrist, or at least read up on Dr. Abram Hoffer's work and protocol.

Good luck.