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Acta Neuropsychiatr. 2017 Apr;29(2):72-79. doi: 10.1017/neu.2016.33. Epub 2016 Jul 11.

Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study.

Author information

1
1Department of Mental Disorder Research,National Institute of Neuroscience,National Center of Neurology and Psychiatry,Tokyo,Japan.
2
3Department of Psychiatry,National Center Hospital,National Center of Neurology and Psychiatry,Tokyo,Japan.
3
4Department of Research and Development,Nutrition Division,Taiyo Kagaku Co. Ltd,Mie,Japan.

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.

CONCLUSION:

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.

KEYWORDS:

l-theanine; anxiety; cognitive function; depression; sleep

PMID:
27396868
DOI:
10.1017/neu.2016.33
[Indexed for MEDLINE]

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