Interconversion of serine and glycine is normal in psychotic patients.

Fasting plasma serine and glycine concentrations, determined by ion-exchange amino acid chromatography, were similar in a large group of psychotic patients with various forms of schizophrenia and in healthy control subjects. Serine and glycine concentrations were also similar in cerebrospinal fluid of psychotic patients and control subjects. The contents of serine and glycine in autopsied brain of three patients with chronic schizophrenia did not differ from contents of these amino acids in control subjects when analyses were limited to brains frozen rapidly after death. These data do not support a recent suggestion (Waziri et al., 1984) that disturbed serine metabolism may be a biological marker and a vulnerability factor for psychosis.