Caffeine beverages linked to improved sustained attention and alertness
A randomized controlled trial found that caffeine-containing beverages and caffeine-matched controls both improved reaction time on attention tests within 45 minutes, with no measurable difference between the energy drink and plain caffeine.
Researchers assigned 116 participants to consume either an energy drink (C4, containing 200 mg caffeine and additional ingredients) or a caffeine-matched control containing only 200 mg caffeine. About 45 minutes after consumption, both groups completed a psychomotor vigilance test to measure sustained attention and reaction time, a memory assessment (MemTrax), and tests of handgrip strength and static muscular endurance (wall-sit hold).
Both the energy drink group and the caffeine control showed significant improvements in reaction time on the vigilance test, indicating enhanced sustained attention and alertness. However, there were no meaningful differences between the groups in this improvement, suggesting the benefit came from caffeine rather than the energy drink's additional ingredients. The energy drink group showed a decrease in memory accuracy on the MemTrax test, though this was not significantly different from the control group. Neither group showed any improvements in handgrip strength or wall-sit endurance. The findings suggest caffeine itself drives the cognitive benefits observed, and energy drink formulations offer no additional cognitive advantage beyond caffeine's effects.
The study's design was notably rigorous: a double-masked randomized trial ruling out expectation effects, with a true caffeine-matched control that isolated whether the energy drink's proprietary blend (taurine, B-vitamins, amino acids, etc.) added anything beyond caffeine's known effects. The reaction time improvement was consistent across both groups—both showed faster responses on the vigilance test—but the lack of between-group difference is the key finding. Interestingly, memory performance actually declined slightly in the energy drink group (% correct scores dropped), though this was not significantly different from controls. The physical performance measures (grip and wall-sit) showed no response to either intervention, consistent with the modest ergogenic claims for caffeine in strength or endurance domains. This aligns with prior literature showing caffeine's primary cognitive effect is on alertness and sustained attention rather than memory consolidation or physical strength.
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Open in Cadence →References
- Consumption of caffeine-containing beverages improves sustained attention and alertness but has no effect on strength or static muscular endurance. — Journal of nutritional science (Read the original)
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