No correlation between plasma NMDA-related glutamatergic amino acid levels and cognitive function in medicated patients with schizophrenia.
OBJECTIVE
Disrupted glutamatergic neurotransmission and cognitive functions are key components in the pathophysiology of schizophrenia. Changes in levels of serum/plasma glutamatergic amino acids, such as glutamate, glycine, and L- and D-serine may be possible clinical markers. Following our recent findings that peripheral blood levels of endogenous glycine, alanine, and especially D-serine may reflect the degree/change in symptoms in schizophrenia, here we investigated whether these plasma amino acid levels may also reflect the status of cognitive functions in schizophrenia.


METHODS
One hundred eight Japanese patients with schizophrenia were evaluated with cognitive assessment batteries at the time that plasma glutamatergic amino acid levels were measured using high-performance liquid chromatography. For analyzing cognitive functions, batteries for reflection prefrontal cortex cognitive functions, verbal fluency tests, the Stroop test, and the digit span forward and backward tests were administered.


RESULTS
Results failed to show a relationship between any plasma glutamatergic amino acid level and cognitive batteries.


CONCLUSIONS
Our results suggest that plasma glutamatergic amino acid levels may be significant biological markers that reflect the condition or a dramatic change at the time of testing, especially in severely affected patients, but they do not reflect cognitive function.
Department of Psychiatry, Juntendo University, School of Medicine, Tokyo, Japan. tohru.oonuma@nifty.ne.jp
Tohru
T
Ohnuma
Yoshie
Y
Sakai
Hitoshi
H
Maeshima
Motoyuki
M
Higa
Ryo
R
Hanzawa
Maiko
M
Kitazawa
Yuri
Y
Hotta
Narimasa
N
Katsuta
Yuto
Y
Takebayashi
Nobuto
N
Shibata
Heii
H
Arai
D000293:Adolescent; D000328:Adult; D000368:Aged; D000409:Alanine / Q000097:blood*; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000627:therapeutic use; D001480:Basal Ganglia Diseases / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis; D015415:Biomarkers / Q000097:blood; D010054:Brief Psychiatric Rating Scale; D018680:Cholinergic Antagonists / Q000009:adverse effects / Q000627:therapeutic use; D003072:Cognition Disorders / Q000097:blood* / Q000175:diagnosis*; D004359:Drug Therapy, Combination; D005260:Female; D005998:Glycine / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012016:Reference Values; D012559:Schizophrenia / Q000097:blood* / Q000175:diagnosis* / Q000188:drug therapy; D012694:Serine / Q000097:blood*; D055815:Young Adult
D014150:Antipsychotic Agents; D015415:Biomarkers; D018680:Cholinergic Antagonists; D012694:Serine; D000409:Alanine; D005998:Glycine