title: Effect of L-theanine on glutamatergic function in patients with schizophrenia.
abstract: OBJECTIVE
  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).
  
  
  METHODS
  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.
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Ota
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Wakabayashi
authors.affiliation: 2Department of Radiology,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Sato
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hori
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Hattori
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Teraishi
authors.affiliation: 3Department of Research and Development,Nutrition Division,Taiyo Kagaku Co., Ltd,Mie,Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Ozawa
authors.affiliation: 3Department of Research and Development,Nutrition Division,Taiyo Kagaku Co., Ltd,Mie,Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Okubo
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kunugi
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D005971:Glutamates / Q000008:administration & dosage*; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000188:drug therapy* / Q000378:metabolism*; D012890:Sleep / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D005971:Glutamates; D005973:Glutamine; D018698:Glutamic Acid; C026166:theanine
keywords: glutamine+glutamate; l-theanine (N-ethyl-l-glutamine); magnetic resonance spectroscopy; schizophrenia