Biochemical Correlates of Behavior in Schizophrenic Patients

Abstract

IN THE FIRST part of this longitudinal study,^3,6 a reduced intake of methionine and tryptophan failed to affect schizophrenic behavior conclusively. During this period of seven months of continuously controlled tryptophan intake we found that increases of urinary indoles occurred independently of tryptophan intake when schizophrenic symptoms in some of the patients grew worse spontaneously. The excretions of catecholamines³⁴ and urinary steroid hormones²⁸ were also elevated with accompanying motor hyperactivity, increased tension and anxiety. The objective of the second part of this investigation was to study the behavioral responses to increases of methionine and tryptophan as well as that of methionine given together with a monoamine oxidase inhibitor (MAOI). Both improvement and worsening of behavior have been reported for normal, schizophrenic, and depressed subjects.^9,14,27,32 It appeared, therefore, of interest to study urinary excretion patterns in relation to amino acid intake and accompanying