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Acta Neuropsychiatr. 2015 Oct;27(5):291-6. doi: 10.1017/neu.2015.22. Epub 2015 Apr 21.

Effect of L-theanine on glutamatergic function in patients with schizophrenia.

Author information

  • 11Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
  • 22Department of Radiology,National Center of Neurology and Psychiatry,Tokyo,Japan.
  • 33Department of Research and Development,Nutrition Division,Taiyo Kagaku Co., Ltd,Mie,Japan.

Abstract

OBJECTIVES:

Glutamatergic dysfunction in the brain has been implicated in the pathophysiology of schizophrenia. Previous studies suggested that L-theanine affects the glutamatergic neurotransmission and ameliorates symptoms in patients with schizophrenia. The aims of the present study were twofold: to examine the possible effects of L-theanine on symptoms in chronic schizophrenia patients and to evaluate the changes in chemical mediators, including glutamate + glutamine (Glx), in the brain by using 1H magnetic resonance spectroscopy (MRS).

METHOD:

The subjects were 17 patients with schizophrenia and 22 age- and sex-matched healthy subjects. L-theanine (250 mg/day) was added to the patients' ongoing antipsychotic treatment for 8 weeks. The outcome measures were the Positive and Negative Syndrome Scale (PANSS), Pittsburgh Sleep Quality Index scores and MRS results.

RESULTS:

There were significant improvements in the PANSS positive scale and sleep quality after the L-theanine treatment. As for MRS, we found no significant differences in Glx levels before and after the 8 week L-theanine treatment. However, significant correlations were observed between baseline density of Glx and change in Glx density by l-theanine.

CONCLUSIONS:

Our results suggest that L-theanine is effective in ameliorating positive symptoms and sleep quality in schizophrenia. The MRS findings suggest that L-theanine stabilises the glutamatergic concentration in the brain, which is a possible mechanism underlying the therapeutic effect.

KEYWORDS:

glutamine+glutamate; l-theanine (N-ethyl-l-glutamine); magnetic resonance spectroscopy; schizophrenia

PMID:
25896423
DOI:
10.1017/neu.2015.22
[PubMed - indexed for MEDLINE]
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