Low concentrations of serum tyrosine in neuroleptic-free schizophrenics with an early onset

Abstract

The concentrations of serum tyrosine, phenylalanine and tryptophan have been determined in 23 male neurolepticfree patients with schizophrenia and 28 male healthy control subjects. Tyrosine was significantly lower in neurolepticfree patients with an early onset (starting before adulthood) than in healthy control subjects ( p<0.05), and the ratio of tyrosine to phenylalanine was significantly lower in neuroleptic-free patients with an early onset than in those with a late onset (starting at adulthood). No significant differences in these three amino acids were found between the patients with a late onset and healthy control subjects. The present findings suggest that there may be a disturbance of balance between tyrosine and phenylalanine in early-onset patients with schizophrenia.