Date of Graduation


Document Type


Degree Level



Health, Human Performance and Recreation


Gray, Michelle

Committee Member/Reader

Ganio, Matthew

Committee Member/Second Reader

Gallagher, Kaitlin


The acute effects of L-theanine and Caffeine on cognition in older adults

Tilley, L., Gray, M., Stone, M., & Binns, A.; Human Performance Lab; University of Arkansas; Fayetteville, AR.

Introduction: Cognitive decline is an impairment that affects many adults and has the potential to be decelerated. Previous studies show that caffeine and L-theanine positively affect cognition in a young population. L-theanine is an amino acid found in tea that produces a relaxation affect. Therefore, the purpose of this study is to determine the acute effects of caffeine and L-theanine on cognition in older adults. Methodology: Fifty-three older adults ages 55 and older participated in this study. Each adult completed the Mini Mental State Exam and participated in a health questionnaire. Both Trails Making Tests (Trails A and Trails B) and the Stroop Color-Word test were administered to measure cognition. Only the trails B and the last portion of the Stroop Color-Word test will be analyzed because they proposed the greatest challenge to the individual. This double-blind controlled trial randomly assigned the participants either 100 mg caffeine, 200 mg of L-theanine, or a placebo (microcrystalline cellulose). After a 60-minute wait period, all tests were repeated and compared to baseline measurements. Results: There was no statistically significant group by time interaction for the Trails B test (p = 0.389). However, there was a time effect interaction between pre-and post-measurements (p = 0.000) showing that time to complete the test decreased. The Stroop Color Word test also had no statistically significant group by time interaction (p = 0.632), but the time effect showed a significant difference (p = 0.001). Each group improved their testing time, but not one specific supplement statistically influenced that improvement. Discussion: Although not statistically significant, Trails B and the Stroop Color Word test showed a decrease in time to complete each test, suggesting that caffeine and L-theanine could affect cognition. The rate of absorbance decreases with age, therefore the wait period could have been longer than the studies where the age range was lower. For some studies that did obtain the results we expected, their dosage was higher and we chose a safe dosage previously administered on a younger population.


cognition, L-theanine, caffeine, cognitive decline, adults