![]() Reaction time is measured in milliseconds. It measures both reaction time and number of responses. It comprises 10 test items with accompanying instructions. company CNS Vital Signs (Morrisville, NC, USA). In addition, to investigate whether the single response was associated with cognitive function after regular ingestion, we compared the results of a single-dose and regular ingestion.Ĭognitrax 24 is a test to evaluate cognitive function, developed by the U.S. ![]() The purpose of this study was to clarify whether the intake of l-theanine, which has a neuroprotective effect, affects the cognitive processes of attention, working memory, and executive function. However, there are many uncertainties about the effects of l-theanine on human cognitive function. Because it suppresses delayed neuronal cell death in the hippocampal Cornu Ammonis 1 area after transient ischemia, 19 reduces excitotoxicity by suppressing the extracellular release of glutamate through inhibition of the glutamine transporter, 20 and promotes neurogenesis, 21 l-theanine can potentially reduce cognitive impairment. L-theanine has been previously reported to have a neuroprotective effect. A further implication would be that the regular intake of the tea is also a factor responsible for the observed improvement in attention. 18 However, in that study, subjects did not consume matcha on the day of the test, suggesting that the improvement in attention was not a transient effect of caffeine but involved other components of the tea. Our previous study indicated that the regular intake of matcha may improve attention. 15, 16 Caffeine transiently improves performance after intake 17 and has a substantial benefit on cognitive function. Green tea contains several substances that affect cognitive function, including caffeine, 12, 13 l-theanine, 7, 14 and catechin. 10, 11 Prevention of AD is an important problem worldwide, and it is necessary to seek a solution. In addition, the Hisayama study warned about a recent increase in the prevalence of Alzheimer's disease (AD). The epidemiologic Nakajima 8 and Tsurugaya studies 9 in Japan indicated that green tea may improve age-related cognitive impairment. 4 Studies in mice indicate that it improves behavior under stress conditions, 5 suppresses deterioration of learning ability under social stress, 6 and improves memory impairment. 2 Among the different tea varieties in Japan, gyokuro and matcha contain more l-theanine than sencha. L-theanine is a nonproteinogenic amino acid contained in green tea 1 and mushrooms. In conclusion, our study indicated that l-theanine may contribute to improving attention, thus enhancing working memory and executive functions. The single dose of l-theanine reduced the reaction time to attention tasks (Stroop test, Part 1), and it increased the number of correct answers and decreased the number of omission errors in working memory tasks (4-Part continuous performance test, Part 4). Evaluations were performed before the intervention, after a single dose of l-theanine, and after 12 weeks of regular intake. Cognitrax was used as a test battery for cognitive function. Mini Mental State Examination-Japanese version score was 24 or higher. ![]() The subjects were Japanese men and women aged 50–69 years. A double-blind, randomized, placebo-controlled study was conducted. This study aimed to clarify which cognitive functions are positively affected by intake of l-theanine. However, the cognitive functions for which theanine is effective are unclear. L-theanine ( γ-glutamylethylamide), an amino acid in green tea, has been shown to affect brain functions by relieving stress disorders, improving mood, and maintaining normal sleep. ![]()
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