ReviewCureus2021
The Cognitive-Enhancing Outcomes of Caffeine and L-theanine: A Systematic Review.
Review in Cureus, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 16 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
16 citing papers in PubMed, 1 synthesis or guideline pooled it, 22 citations in OpenAlex.
- The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic review.BMC psychiatry · 2024Pooled it
- Methylphenidate (Ritalin) does not improve exam performance in an experimental setting.Psychopharmacology · 2026Trial
- Article
- Habitual Tea Consumption Is Associated with a Low Prevalence of Self-Reported Lifetime History of Depression in Taiwanese Population Study.Nutrients · 2026Article
- Effects of L-theanine on cognition, mood and sleep: evidence from human trials.Frontiers in nutrition · 2026Review
- The association between caffeine consumption and memory, anxiety, and stress levels among students: A crosssectional study.Journal of education and health promotion · 2026Article
- Effects of Caffeine on NFL Combine-Like Tests in Undergraduate Students.International journal of exercise science · 2026Article
- Promising, but Not Completely Conclusive-The Effect of l-Theanine on Cognitive Performance Based on the Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Clinical Trials.Journal of clinical medicine · 2025Review
- Determination of L-Theanine and Caffeine Contents in Tea Infusions with Different Fermentation Degrees and Brewing Conditions Using the Chromatographic Method.Foods (Basel, Switzerland) · 2025Article
- Review
- Research progress of tDCS in the treatment of ADHD.Journal of neural transmission (Vienna, Austria : 1996) · 2025Review
- New insights into healthy ageing, inflammageing and frailty using metabolomics.Frontiers in aging · 2024Review
- Article
- The Relationship between Beverages Consumption and Cognitive Impairment in Middle-Aged and Elderly Chinese Population.Nutrients · 2023Article
- Assessing brain function in stressed healthy individuals following the use of a combination of green tea, Rhodiola, magnesium, and B vitamins: an fMRI study.Frontiers in nutrition · 2023Article
- The therapeutic potential of matcha tea: A critical review on human and animal studies.Current research in food science · 2023Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
10 authors at 7 institutions in 6 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Attention-deficit hyperactivity disorder (ADHD) affects multiple cognitive domains, including impaired attention, hyperactivity, and increased impulsivity. According to the CDC, 9.4% of children between 2 and 17 years old have been diagnosed with ADHD. Neurotransmitters such as noradrenaline and dopamine have been suggested as crucial players in the pathophysiology of ADHD and are often targets of modern medication. Adenosine receptors types A1 and A2a in the brain are inhibited by caffeine: a stimulant known to augment attention by increasing cholinergic and dopaminergic transmission. The cognitive function of attention is also enhanced by the amino acid: L-theanine. The mechanism of action is that it behaves like a glutamate reuptake inhibitor while also acting in the hippocampus as a competitive low-affinity glutamate receptor antagonist. It's also shown to have a neuroprotective effect by its action on the gamma aminobutyric acid (GABA)-A receptors. Our systematic review investigates the literature and clinical trials on the cognitive-enhancing effects of caffeine and L-theanine.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.