LOW CONCENTRATIONS OF SERUM TYROSINE IN NEUROLEPTIC-FREE SCHIZOPHRENICS WITH AN EARLY-ONSET

The concentrations of serum tyrosine, phenylalanine and tryptophan hav e been determined in 23 male neuroleptic-free patients with schizophre nia and 28 male healthy control subjects. Tyrosine was significantly l ower in neuroleptic-free patients with an early onset (starting before adulthood) than in healthy control subjects (p<0.05), and the ratio o f tyrosine to phenylalanine was significantly lower in neuroleptic-fre e patients with an early onset than in those with a late onset (starti ng at adulthood). No significant differences in these three amino acid s were found between the patients with a late onset and healthy contro l subjects. The present findings suggest that there may be a disturban ce of balance between tyrosine and phenylalanine in early-onset patien ts with schizophrenia.