l -Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging study

Kahathuduwa, Chanaka N.; Dhanasekara, Chathurika S.; Chin, Shao-Hua; Davis, Tyler; Weerasinghe, Vajira S.; Dassanayake, Tharaka L.; Binks, Martin

doi:10.1016/j.nutres.2017.11.002

Cited by 26 publications

(23 citation statements)

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“…Even though we observed improvements in reaction times (i.e. faster reaction times) of sustained attention tasks with the administration of l -theanine, caffeine and their combination among healthy adults in our previous studies, we did not observe improvements in hit rate or the error rate 26 , 33 . However, in the present study, l -theanine, caffeine and their combination improved the hit rate, but not reaction times in the Go/NoGo task.…”

Section: Discussioncontrasting

confidence: 91%

“…Furthermore, administration of caffeine was associated with an acute reduction of impulsivity in Spontaneous Hypertensive Rats, an animal model of ADHD 31 and also the alcohol-associated impulsivity in healthy adults 32 . While there are hardly any animal studies on the effects of l -theanine on sustained attention or inhibitory control, our prior experience 26 , 33 corroborates the findings of many others (e.g. Refs.…”

Section: Introductionsupporting

confidence: 90%

“…However, the evidence regarding the effects of l -theanine–caffeine combination on sustained attention have been fairly consistent in suggesting the utility of both compounds in moderately improving measures of sustained attention in healthy adults 36 . Our prior studies conducted on healthy adults 26 , 33 , corroborate the findings of others 34 , 37 to suggest that l -theanine–caffeine combination improves sustained attention in healthy adults, yet the relative contribution of l -theanine and caffeine to the improvements appear to largely depend on the task demands (e.g. difficulty, emphasis on accuracy vs. speed).…”

Section: Introductionsupporting

confidence: 87%

“…To our knowledge, the present study is the first to examine the effects of l -theanine–caffeine combination on overall cognition using a standardized validated test battery such as the NIH Cognition Toolbox. However, the improvements we observed in overall cognition composite of NIH Toolbox with l -theanine–caffeine combination is not surprising given that multiple interventional trials and meta-analyses of such trials have suggested that particularly the combination of l -theanine and caffeine seems to improve a variety of cognitive functions 25 – 27 , 33 , 36 , 37 . For instance, Camfield et al performed a systematic review and meta-analysis of studies that have examined the cognitive effects of the l -theanine–caffeine combination to suggest that intake of a combination of l -theanine and caffeine seems to improve attention switching and intersensory attention in healthy adults 36 .…”

Section: Discussionmentioning

confidence: 70%

“…We observed that administration of each of ~ 2.5 mg/kg body of l -theanine and ~ 2.0 mg/kg of caffeine as well as their combination improves performance in a visual sustained attention task 26 . In a subsequent functional magnetic resonance imaging (fMRI) study, this observation was replicated and both l -theanine and caffeine were found to decrease task-related reactivity of DMN, possibly decreasing mind wandering 33 . Therefore, l -theanine and caffeine seem to have a potential to be used to alleviate deficits of sustained attention in children with ADHD.…”

Section: Introductionmentioning

confidence: 79%

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Effects of l-theanine–caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT

Kahathuduwa

Wakefield

West

et al. 2020

Sci Rep

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We examined the acute effects of l -theanine, caffeine and their combination on sustained attention, inhibitory control and overall cognition in boys with attention deficit hyperactivity disorder (ADHD). l -Theanine (2.5 mg/kg), caffeine (2.0 mg/kg), their combination and a placebo were administered in a randomized four-way repeated-measures crossover with washout, to five boys (8–15 years) with ADHD. Functional magnetic resonance imaging (fMRI) was performed during a Go/NoGo task and a Stop-signal task ~ 1 h post-dose. NIH Cognition Toolbox was administered ~ 2 h post-dose. Treatment vs. placebo effects were examined in multi-level mixed-effects models. l -Theanine improved total cognition composite in NIH Cognition Toolbox (p = 0.040) vs. placebo. Caffeine worsened and l -theanine had a trend of worsening inhibitory control (i.e. increased Stop-signal reaction time; p = 0.031 and p = 0.053 respectively). l -Theanine–caffeine combination improved total cognition composite (p = 0.041), d-prime in the Go/NoGo task (p = 0.033) and showed a trend of improvement of inhibitory control (p = 0.080). l -Theanine–caffeine combination was associated with decreased task-related reactivity of a brain network associated with mind wandering (i.e. default mode network). l -Theanine–caffeine combination may be a potential therapeutic option for ADHD-associated impairments in sustained attention, inhibitory control and overall cognitive performance.

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Section: Discussioncontrasting

confidence: 91%

Section: Introductionsupporting

confidence: 90%

Section: Introductionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 79%

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Effects of l-theanine–caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT

Kahathuduwa

Wakefield

West

et al. 2020

Sci Rep

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Mental Performance and Sport: Caffeine and Co-consumed Bioactive Ingredients

Kennedy

Wightman

2022

Sports Med

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The plant defence compound caffeine is widely consumed as a performance enhancer in a sporting context, with potential benefits expected in both physiological and psychological terms. However, although caffeine modestly but consistently improves alertness and fatigue, its effects on mental performance are largely restricted to improved attention or concentration. It has no consistent effect within other cognitive domains that are important to sporting performance, including working memory, executive function and long-term memory. Although caffeine’s central nervous system effects are often attributed to blockade of the receptors for the inhibitory neuromodulator adenosine, it also inhibits a number of enzymes involved both in neurotransmission and in cellular homeostasis and signal propagation. Furthermore, it modulates the pharmacokinetics of other endogenous and exogenous bioactive molecules, in part via interactions with shared cytochrome P450 enzymes. Caffeine therefore enjoys interactive relationships with a wide range of bioactive medicinal and dietary compounds, potentially broadening, increasing, decreasing, or modulating the time course of their functional effects, or vice versa. This narrative review explores the mechanisms of action and efficacy of caffeine and the potential for combinations of caffeine and other dietary compounds to exert psychological effects in excess of those expected following caffeine alone. The review focusses on, and indeed restricted its untargeted search to, the most commonly consumed sources of caffeine: products derived from caffeine-synthesising plants that give us tea (Camellia sinensis), coffee (Coffea genus), cocoa (Theabroma cacao) and guaraná (Paullinia cupana), plus multi-component energy drinks and shots. This literature suggests relevant benefits to mental performance that exceed those associated with caffeine for multi-ingredient energy drinks/shots and several low-caffeine extracts, including high-flavanol cocoa and guarana. However, there is a general lack of research conducted in such a way as to disentangle the relative contributions of the component parts of these products.

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