title: Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study.
abstract: OBJECTIVE
  l-theanine, an amino acid uniquely contained in green tea (Camellia sinensis), has been suggested to have various psychotropic effects. This study aimed to examine whether l-theanine is effective for patients with major depressive disorder (MDD) in an open-label clinical trial.
  
  
  METHODS
  Subjects were 20 patients with MDD (four males; mean age: 41.0±14.1 years, 16 females; 42.9±12.0 years). l-theanine (250 mg/day) was added to the current medication of each participant for 8 weeks. Symptoms and cognitive functions were assessed at baseline, 4, and 8 weeks after l-theanine administration by the 21-item version of the Hamilton Depression Rating Scale (HAMD-21), State-Trait Anxiety Inventory (STAI), Pittsburgh Sleep Quality Index (PSQI), Stroop test, and Brief Assessment of Cognition in Schizophrenia (BACS).
  
  
  RESULTS
  HAMD-21 score was reduced after l-theanine administration (p=0.007). This reduction was observed in unremitted patients (HAMD-21>7; p=0.004) at baseline. Anxiety-trait scores decreased after l-theanine administration (p=0.012) in the STAI test. PSQI scores also decreased after l-theanine administration (p=0.030) in the unremitted patients at baseline. Regarding cognitive functions, response latency (p=0.001) and error rate (p=0.036) decreased in the Stroop test, and verbal memory (p=0.005) and executive function (p=0.016) were enhanced in the BACS test after l-theanine administration.
  
  
  CONCLUSIONS
  Our study suggests that chronic (8-week) l-theanine administration is safe and has multiple beneficial effects on depressive symptoms, anxiety, sleep disturbance and cognitive impairments in patients with MDD. However, since this is an open-label study, placebo-controlled studies are required to consolidate the effects.
authors.affiliation: 1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Hidese
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: 3Department of Psychiatry,National Center Hospital,National Center of Neurology and Psychiatry,Tokyo,Japan.
authors.forename: Takamasa
authors.initials: T
authors.lastname: Noda
authors.affiliation: 4Department of Research and Development,Nutrition Division,Taiyo Kagaku Co. Ltd,Mie,Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Ozawa
authors.affiliation: 4Department 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; D001007:Anxiety / Q000150:complications / Q000188:drug therapy; D003071:Cognition / Q000187:drug effects; D003865:Major Depressive Disorder / Q000150:complications / Q000188:drug therapy*; D005260:Female; D005971:Glutamates / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D057190:Stroop Test; D016896:Treatment Outcome
chemical_list: D005971:Glutamates; C026166:theanine
keywords: 
                 l-theanine; anxiety; cognitive function; depression; sleep