Dose-Dependent Effects of Caffeine on Cognitive Performance, Hormonal Regulation, and Gut Microbiota across Adulthood
Dose-Dependent Effects of Caffeine on Cognitive Performance and Gut Microbiota
DOI:
https://doi.org/10.54393/df.v7i2.213Keywords:
Caffeine, Cognitive Performance, Reaction Time, Gut Microbiota, Cortisol, Adrenaline, Dose-ResponseAbstract
Caffeine is a psychoactive drug that has a wide range of uses, including being consumed to increase alertness and cognitive function. Recently, there has also been some evidence that caffeine can influence biochemical markers and gut microbiota composition, which also requires further research. Objectives: To assess the dose-dependent effects of caffeine on reaction time, alertness, and cognitive performance in various demographic groups and to investigate its biochemical and microbiological effects. Methods: This study used a double-masked, quasi-experimental design. Participants were given caffeine in low (50 mg), moderate (100 mg), or high (200 mg) doses in separate sessions with a 48-hour washout period and placebo control. Reaction time, self-reported alertness, and cognitive task performance were measured. The blood and stool samples were taken before and after caffeine consumption to assess cortisol, adrenaline, and gut microbiota profiles using 16S rRNA sequencing. Results: No statistically significant differences in reaction time and alertness were observed between any of the caffeine doses (p>0.050). A significant reduction in cortisol levels was observed at the higher dose (p=0.048), but no change in adrenaline levels was seen. No significant differences in the relative abundance of bacterial phyla were found, except for Firmicutes, which was moderately up-regulated by caffeine (p=0.049). Performance improvements showed trends favoring younger adults, though these were not statistically significant. Conclusions: This hypothesis‑generating study demonstrates trends toward dose‑dependent hormonal and microbial modulation (notably a reduction in cortisol at 200 mg and an increase in Firmicutes at 100 mg). However, no statistically significant cognitive enhancements were observed. These preliminary findings warrant confirmation in larger, adequately powered studies before clinical recommendations can be made.
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