Plasma Serine to Cysteine Ratio as a Biological Marker for Psychosis

Abstract

SummaryIn a study of plasma amino acids in psychiatric patients, serine to cysteine (S/C) ratio was higher (S/C = 1.57±0.28) in 57 psychotics compared to 27 nonpsychotics (S/C = 1.06±0.23). This difference was highly significant at P <0.001. Psychotic patients were given a psychosis score (p score) of 1–4, The S/C ratios of individual patients were significantly correlated to their p scores (r = 0.65, P <0.001). S/C ratios were not related to diagnosis, age, sex, food intake and medications. When the initial S/C ratio and p scores of 22 patients were compared to their S/C ratio and p score at the time when they were improved and ready to be discharged, there was a concomitant fall both in S/C ratios and p scores suggesting the high S/C ratios may be indicative of a state rather than a trait characteristic. Our findings lead us to the conclusion that S/C ratios may provide a marker for the presence of psychosis and an index of its severity.