@DkJoe2 True. There's a fluorinated serotonin releasing agent, can't remember the name, that induces OCD-like behaviors in studies.

I heard that peat claims methyl groups are generally unnecessary and contribute to the aging process through methylation of nucleic acids.

What are your opinions on choline (hard-core methyl donor)?

On the subreddits r/Nootropics and r/Supplements there's hundreds of posts on the cholinergics Choline, Alpha-Gpc causing serious depression in their users. Another one, that affected me and many posters as well, is eggs. In some countries (inc US) they're fortified with choline at the chicken feed. Its need to be supplemented is controversial as the tiny amounts needed are synthesized readily.

There's lots of discussion on long hauler subreddits and cfs forums on cholinesterase deficiency. Ray Peat has an article on rising acethylcholine being associated with learned helplessness, and mentions that bright light exposure during day and an explorative, creative lifestyle seems to help this.

Most people are deficient in cholinesterase from organophosphate exposure.

Other methyl donors that cause some people problems are methyl-b12 and methyl-folate. Lots of reddit posts of people losing it on them.

Over-methylation is also linked to mold exposure (inc candida) and copper toxicity [linked to an obscure condition called histapenia, seems to be the cause of the "hangover effect" subreddit]