50 Esports Pros, 3 Compounds, Zero Anxiety: Inside the Clinical Trial That Proves the Modern Nootropic Stack Beats Caffeine Alone

Theacrine Benefits: Inside the Clinical Trial That Proved a 3-Compound Nootropic Stack Beats Caffeine Alone

Fifty esports athletes walked into a lab at Nova Southeastern University. They were randomized into a crossover trial, dosed with either caffeine alone, a three-compound combination, or a placebo, and tested on reaction time, inhibitory control, mood, and brain activity. The results, published in Cureus in December 2021, showed that the caffeine-theacrine-methylliberine combination (called "CDT" in the paper) improved cognitive performance on two validated tasks while raising alertness, all without the anxiety spike that caffeine alone produced.

If you've been searching for evidence-backed theacrine benefits, this is the paper to read. It's also the clinical foundation behind a new generation of nootropic products designed to replace the caffeine-only approach most gamers and knowledge workers still rely on.

Here's what the study found, why it matters, and what it means for your stack.

Key Takeaways

• CDT beat caffeine alone on the Flanker Test of Inhibitory Control (p < 0.01) and the Psychomotor Vigilance Task reaction time (p = 0.044), while caffeine alone did not reach statistical significance on either measure compared to pre-dose.
• Caffeine alone increased self-reported anxiety compared to placebo. The CDT combination did not. Instead, CDT raised self-reported alertness.
• EEG data showed CDT increased cortical delta and theta power, markers associated with internal attention and cognitive control.
• The three compounds in the CDT stack, caffeine, theacrine (TeaCrine), and methylliberine (Dynamine), work through overlapping but distinct mechanisms on adenosine and dopamine pathways.

The Study: Design and Methods

The Tartar et al. 2021 trial was a repeated-measures, randomized crossover study. That design matters. Every participant served as their own control, cycling through all three conditions across three separate sessions spaced one week apart. This eliminates the noise that comes from comparing different people with different baseline metabolisms.

Who Was Tested

Fifty male amateur egamers, mean age 20.5 years, each playing at least 10 hours of first-person video games per week. The researchers also genotyped every participant for CYP1A2*1F allele status (the gene that determines how fast you metabolize caffeine) to check whether fast or slow metabolizers responded differently.

The Three Conditions

What Was Measured

The battery was extensive:

• Flanker Test of Inhibitory Control and Attention (NIH Toolbox): measures your ability to focus on a target while ignoring distracting stimuli. This is the exact cognitive skill that separates a good FPS player from a great one.
• Psychomotor Vigilance Task (PVT): a simple reaction-time test that measures sustained attention and behavioral alertness. Widely used in sleep research and military performance testing.
• Digit Symbol Substitution Test (DSST): measures processing speed.
• Self-reported mood: anxiety, alertness, and headache via the MAPSS scale.
• Biomarkers: salivary cortisol, salivary alpha-amylase (sAA), heart rate, blood pressure.
• EEG: alpha, beta, delta, and theta frequency band power during cognitive tasks.

The Results: Where CDT Pulled Ahead

Flanker Test (Inhibitory Control)

The CDT combination produced a statistically significant improvement in Flanker performance from pre-dose to post-dose (p < 0.01). Neither caffeine alone nor placebo reached significance on this measure. The researchers noted that "CDT augments the attention and inhibitory control on flanker performance because dopaminergic modulation of the DLPFC is critical for attention and inhibition."

Whether you search for theacrine vs caffeine or TeaCrine vs caffeine, this is the controlled test you've been looking for. Caffeine at 125 mg didn't move the needle on inhibitory control. Add theacrine and methylliberine at the same caffeine dose, and it did.

PVT Reaction Time

CDT produced a significant decrease (improvement) in PVT reaction time from pre to post-dose (p = 0.044). Caffeine alone and placebo did not reach significance. The PVT is one of the most validated measures of behavioral alertness in neuroscience, used everywhere from NASA astronaut screening to military readiness testing.

Mood: Alertness Up, Anxiety Flat

This is where the story gets interesting for anyone who has ever felt wired but scattered after too much coffee. Compared to placebo, caffeine alone increased self-reported anxiety. The CDT combination instead increased self-reported alertness without any anxiety increase. CDT also produced fewer self-reported headaches than caffeine alone.

EEG and Cortisol

The CDT condition increased cortical delta power and theta frequency during cognitive tasks. Delta power is associated with attention to internal processing; theta is linked to cognitive control. The CDT group also showed increased cortisol, which in this context reflects energy mobilization rather than stress (cortisol rises acutely during focused cognitive effort, not just during distress).

Why the Combination Works: The Biochemistry of Theacrine Benefits

The three compounds in CDT aren't just "more stimulants stacked together." They operate on overlapping but pharmacologically distinct pathways.

Theacrine (TeaCrine)

Theacrine is a purine alkaloid structurally similar to caffeine (1,3,7,9-tetramethyluric acid). A 2012 study published in Pharmacology Biochemistry and Behavior demonstrated that theacrine acts as an adenosine receptor antagonist (like caffeine) but also modulates dopamine signaling through D1 and D2 receptors. The same study found that chronic theacrine administration did not produce locomotor tolerance or sensitization in animal models, a sharp contrast to caffeine's well-documented tolerance curve.

An eight-week human safety trial confirmed the non-habituation finding: participants taking TeaCrine daily at doses up to 300 mg showed no evidence of the tachyphylaxis (rapid tolerance buildup) that is typical of caffeine and other stimulants.

This is the core theacrine benefit that separates it from caffeine. Same receptor family, different binding kinetics, no tolerance ramp.

Methylliberine (Dynamine)

Methylliberine is another purine alkaloid from the same kucha tea leaf family. Its defining characteristic is speed. Research indicates methylliberine reaches peak plasma concentration in approximately 0.6 to 0.9 hours with a half-life of about 1.4 hours, compared to caffeine's 4-5 hour half-life. It acts as a negative allosteric modulator on adenosine receptors, which may explain why it produces less tolerance buildup than caffeine's direct antagonism.

In the Tartar 2021 study, methylliberine's fast onset likely contributed to the acute cognitive improvements on the Flanker and PVT tasks, while theacrine's longer duration extended the effect window.

The Layered Effect

Think of it as a relay, not a pile-on. Methylliberine fires first (peak at ~30-45 minutes), caffeine sustains the middle window (peak at 30-60 minutes, half-life 4-5 hours), and theacrine extends the tail (longer half-life, no tolerance). The Tartar study measured acute effects, but the pharmacokinetic profiles suggest the combination creates a smoother, longer performance curve than any single compound.

A separate trial on 48 tactical personnel reinforced this: a caffeine-methylliberine-theacrine combination (150 mg / 100 mg / 50 mg) matched the vigilance reaction-time benefits of 300 mg caffeine alone, with more favorable hemodynamic responses (less blood pressure elevation).

What About the Follow-Up? The Evans 2023 FPS Study

Tartar's lab didn't stop at cognitive tasks. A 2023 follow-up study published in Cureus (Evans et al.) tested the same CDT combination under actual first-person shooter gameplay conditions. The CDT group showed faster reaction times during gameplay without sacrificing accuracy, suggesting a better speed-accuracy tradeoff than either caffeine alone or placebo. This is the TeaCrine Dynamine clinical trial data that moves the findings from abstract cognitive tests to the performance context gamers actually care about.

Honest Limitations

Good science means acknowledging what a study doesn't prove.

• Male-only sample: All 50 participants were young men. The results may not generalize to women or older adults.
• Single-dose, acute design: The study measured one-time dosing effects. It did not test chronic daily use (though the separate eight-week TeaCrine safety trial provides some reassurance on that front).
• Esports-specific population: These were experienced gamers playing 10+ hours per week. Baseline cognitive performance and familiarity with sustained attention tasks may differ from the general population.
• Funded by Compound Solutions: The study was supported by the manufacturer of TeaCrine and Dynamine. The crossover design and objective biomarkers (EEG, cortisol) reduce but don't eliminate potential bias.

From Lab to Lip: How This Research Translates to Daily Use

The Tartar 2021 study used 125 mg caffeine, 50 mg theacrine, and 75 mg methylliberine, a high-acute lab dose designed to detect effects in a single session. That's not the same as what you'd want for daily, sustained cognitive support.

Roon was built around the same three active compounds from this research, plus L-theanine, in doses calibrated for repeated daily use rather than a single lab spike:

The dosing difference is intentional. A daily-use product needs to sit below the threshold where tolerance and side effects start compounding. The ratio and interplay between compounds matters more than raw milligrams.

The addition of L-theanine addresses the one gap in the Tartar study. L-theanine promotes alpha brain wave activity, the frequency band associated with relaxed alertness. A 2008 study in Nutritional Neuroscience found that L-theanine combined with caffeine improved attention task performance and increased alpha-band activity beyond what either compound achieved alone. It's the smoothing layer that the CDT formulation didn't include.

Roon's sublingual delivery also changes the absorption equation. Sublingual administration bypasses hepatic first-pass metabolism, allowing compounds to enter the bloodstream directly through the oral mucosa. The result is faster onset and higher bioavailability compared to a swallowed capsule.

Related from Roon

• Beyond the 6-Hour Window: How Multi-Compound Nootropic Stacks Engineer All-Day Cognitive Endurance
• Studying vs. Lifting vs. Boardroom: How to Match Your Nootropic Stack to the Cognitive Task
• Most Focus Supplements Are Marketing Hype: The 4 Ingredients With Real Clinical Backing (And Why Roon Built Around All Four)

The Bottom Line

The Tartar 2021 esports cognitive performance study is one of the clearest demonstrations that caffeine alone is not the optimal approach to sustained cognitive performance. Adding theacrine and methylliberine to the same caffeine base produced better inhibitory control, faster reaction times, higher alertness, and lower anxiety than caffeine by itself. The EEG and cortisol data give those behavioral findings a physiological foundation.

If you've been relying on caffeine alone, whether from coffee, energy drinks, or single-ingredient pouches, the research points in a clear direction: the combination outperforms the solo act.

Roon is the consumer-format expression of exactly this clinical research. Same three core actives, plus L-theanine, in a sublingual pouch designed for daily use. You can read the full Tartar et al. 2021 study here.