Relation of plasma glycine, serine, and homocysteine levels to schizophrenia symptoms and medication type.
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.
Neeman
Guy
G
Ezrath Nashim-Herzog Memorial Hospital, P.O. Box 3900, Jerusalem 91035, Israel.
Blanaru
Monica
M
Bloch
Boaz
B
Kremer
Ilana
I
Ermilov
Marina
M
Javitt
Daniel C
DC
Heresco-Levy
Uriel
U
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
D000596:Amino Acids; D014150:Antipsychotic Agents; D016194:Receptors, N-Methyl-D-Aspartate; D006710:Homocysteine; D012694:Serine; D003024:Clozapine; D005998:Glycine