This subject is a tangled web of sorts. Nevertheless some brilliant work has been done. Osmond and Smythies proposed a brilliant hypothesis suggesting faulty epinephrine metabolism. Wooley and Shaw proposed a serotonin blockade, but the evidence for this is not convincing. Kety's theory of pathological transmethylation apppears to have been borrowed from Osmond & Smythies. Toxic factors have been reported by Heath, Bergen, and Frohman.
Peter Beckett and Jaques Gottlieb were brilliant Detroit researchers. They used electrophoresis to analyze blood proteins in schizophrenia. They found two toxic proteins. One produced hemolysis and the other affected the L/P ratio. The L/P ratio was used as a measurement of metabolism. They called one of their proteins "factor 1". Factor 1 delays climbing time in rats. It also raises the amino acid uptake by cells according to Frohman. Factor 3 causes hemolysis.
Heath's work was very controversial but valuable. He found an anti-septal substance, meaning that the factor attacked the septal area of the brain. Similar work was reported in Russia by Kolaskina.
Beckett & Gottlieb suggested that there may be "more than one kind of schizophrenia". This makes the situation even more complicated. There does appear to be at least one toxic factor, and perhaps more. The toxic factor appears to be made up of amino acids, including methionine.
The factor causes amino acids to flood the cells. Thus amino acids appear to be double trouble. Perhpas a diet low in amino acids should be tried. Osmond suggested orthomolecular psychiatry, meaning the use of nutrition. This view was shared by Hoffer and by Pauling.