Dose-response effect of L-theanine on psychomotor speed, sustained attention, and inhibitory control: a double-blind, placebo-controlled, crossover study

被引:2
|
作者
Dassanayake, Tharaka L. [1 ,2 ]
Wijesundara, Devasmitha [1 ]
Kahathuduwa, Chanaka N. [3 ,4 ]
Weerasinghe, Vajira S. [1 ]
机构
[1] Univ Peradeniya, Fac Med, Dept Physiol, Peradeniya 20400, Sri Lanka
[2] Univ Newcastle, Sch Psychol Sci, Callaghan, NSW, Australia
[3] Texas Tech Univ, Sch Med, Dept Psychiat, Hlth Sci Ctr, Lubbock, TX USA
[4] Texas Tech Univ, Hlth Sci Ctr, Dept Lab Sci & Primary Care, Lubbock, TX 79430 USA
关键词
Theanine; attention; cognitive functions; reaction time; sustained attention; inhibitory control; stop-signal task; placebo-controlled trial; UNIQUE AMINO-ACID; STOP-SIGNAL; GREEN TEA; CAFFEINE; COMBINATION; COGNITION; CONSUMPTION; TASK;
D O I
10.1080/1028415X.2022.2136884
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Background: L-theanine is a non-protein-forming amino acid found in tea. Previous research shows high doses (100-400 mg) of L-theanine enhances attention, mainly by reducing mind wandering and distracter processing. We hypothesized that these indirect mechanisms could significantly improve the performance of low-level attentional tasks, whereas the relative contribution could be less in complex attentional tasks that require active, higher-order processing of target stimuli. Methods: To test this hypothesis, we conducted a double-blind, placebo-controlled, counterbalanced, four-way crossover study in 32 healthy young adults, where we compared the effects of three doses of L-theanine (100, 200 and 400 mg) with a placebo (distilled water), administered before and 50 min after dosing, on three attentional tasks from the Cambridge Neuropsychological Test Automated Battery [viz. Reaction Time (RTI)-visuomotor speed, Rapid Visual Information Processing (RVP)-sustained attention, and Stop Signal Task (SST)-inhibitory control]. Results were analyzed in dose x time repeated measures ANOVA models, with subsequent pairwise comparisons. Results: Active doses significantly improved reaction times in the RTI (100-200 mg) and RVP (200-400 mg) tasks from baseline (p < 0.05), but once controlled for the change-from-baseline caused by placebo, only the RTI simple reaction times showed significant improvements, following 100 mg (Delta = 16.3 ms, p = 0.009) and 200 mg (Delta = 16.9 ms, p = 0.009) of L-theanine. Conclusions: Consistent with our hypothesis, these findings suggest that L-theanine significantly improves attention in simple visuomotor tasks, but not in more complex sustained attention tasks, or executive control tasks that require top-down inhibition of pre-active responses.
引用
收藏
页码:1138 / 1146
页数:9
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