Before emigrating the the US, I lived in the Highlands of Scotland, where I worked at a mental hospital, as resident psychologist, where I met and worked with a doctor who used diet to control many of the disorders patients suffered from.
Relevant here is the treatment, at that time regarded as crazy, but with amazing results, whereby the patient was directed to follow a strict diet without any greens at all, lettuce is not just bad for skin disorders, it is very bad for schizophrenia, along with any and all cruciferous vegetables. If all nightshades were avoided also, the results were stunning - the condition was controlled extremely well, resulting in reduction of medication, and introduction to local group housing. I have been unable to find any documentation of the 'treatment' as the hospital in question is no longer open.  My familiarity with the results, however, convinced me to recommend this 'diet' to patients in the US.