title: Relation of plasma glycine, serine, and homocysteine levels to schizophrenia symptoms and medication type.
abstract: OBJECTIVE
  Altered glycine and homocysteine levels may contribute to N-methyl-D-aspartate receptor dysfunction in schizophrenia. The authors measured plasma levels of these amino acids in a group of patients with chronic schizophrenia and related them to the patients' symptom profiles and types of antipsychotic medication.
  
  
  METHODS
  Plasma levels of amino acids in 94 patients with schizophrenia were compared with those in 34 age- and sex-matched normal subjects. The Positive and Negative Syndrome Scale was used to evaluate the patients' psychopathology.
  
  
  RESULTS
  Plasma glycine levels and glycine-serine ratios were lower and homocysteine levels were higher in patients than in comparison subjects. Low glycine levels correlated with a greater number of negative symptoms. The glycine-serine ratios of normal subjects and patients being treated with clozapine did not differ significantly.
  
  
  CONCLUSIONS
  These findings support the hypothesis that altered levels of glycine and homocysteine may coexist in patients with schizophrenia and contribute to pathophysiological aspects of this illness.
authors.affiliation: Ezrath Nashim-Herzog Memorial Hospital, P.O. Box 3900, Jerusalem 91035, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Neeman
authors.forename: Monica
authors.initials: M
authors.lastname: Blanaru
authors.forename: Boaz
authors.initials: B
authors.lastname: Bloch
authors.forename: Ilana
authors.initials: I
authors.lastname: Kremer
authors.forename: Marina
authors.initials: M
authors.lastname: Ermilov
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Javitt
authors.forename: Uriel
authors.initials: U
authors.lastname: Heresco-Levy
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood* / Q000502:physiology; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D003024:Clozapine / Q000627:therapeutic use; D005260:Female; D005998:Glycine / Q000097:blood / Q000502:physiology; D006710:Homocysteine / Q000097:blood / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D012559:Schizophrenia / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D012565:Schizophrenic Psychology; D012694:Serine / Q000097:blood / Q000502:physiology
chemical_list: D000596:Amino Acids; D014150:Antipsychotic Agents; D016194:Receptors, N-Methyl-D-Aspartate; D006710:Homocysteine; D012694:Serine; D003024:Clozapine; D005998:Glycine