The Effects of L-Theanine Supplementation on Cognition in Older Adults

Date of Graduation


Document Type


Degree Name

Bachelor of Science

Degree Level



Health, Human Performance and Recreation


Gray, Michelle

Committee Member/Reader

Fort, Inza

Committee Member/Second Reader

Hunt, Sharon


Context: Currently, more than 16 million Americans are living with cognitive impairment. With the growing number of older adults in the US, the number is expected to increase 4-fold by 2050. Reduced cognition leads to decreased memory recall and information processing which can negatively impact mood and decrease quality of life. Therefore, improving cognition in older adults is imperative. Objective: The purpose of this study was to longitudinally assess the cognitive and mood effects of L-Theanine in older adults. It is hypothesized that L-Theanine will enhance cognition and mood in older adults. Design: The design for this study was a randomized, double-blind placebo trial. Setting: Each subject was tested either in the Human Performance Lab or Butterfield Trail Village for all assessments. Participants: Fifteen older adults (>55 y) who scored greater than a 24 on the MMSE participated in this study. The women (n=9) and men (n=6) who participated were from the Northwest Arkansas area and had an average BMI of 24.3 kg/m2. Interventions: The three cognitive tests used were the Trail Making Test parts A and B as well as the Stroop Color-Word test. BRUMS was utilized for mood assessment. There were two visits used to assess cognition and mood. The first assessment was used as a means of determining the subject’s baseline. The second assessment occurred after 28 days of supplementation. Subjects consumed one pill each day, in the morning (within 60 minutes of waking), for the duration of four weeks. The participants were randomly assigned L-Theanine (200mg) or Microcrystalline Cellulose (placebo). Main Outcome Measures: Dependent variables used to assess cognition and mood were the participant’s scores on the following assessments: Trails A and B, Stroop Color-Word, and BRUMS. Time of completion was used for the score on Trails A and B. Scoring of the Stroop Color-Word assessment was scaled using the participant’s age and completion time. Scoring of BRUMS was scaled using the participants’ responses to self-perception of 32 adjectives. Repeated measures ANOVA was used to test for statistical significance (p= .05). Cohen’s d was used to assess effect size. Results: Statistical significance was not found in any of the outcome measures; however, there were statistical trends for outcome measures in Stroop (3rd assessment) and Trails A. There was a moderate effect for enhancing Stroop 3 (d= 0.43), anger (d= 0.53), happiness (d= 0.61), and calmness (d= 0.69) and large effect for improving Trails A (d= 1.00), tension (d= 1.30), and depression (d= 0.90). Conclusion: The results of this study indicate L-Theanine may be beneficial for improving cognition and mood in older adults. It would be useful for future studies to investigate the effects of L-Theanine using a larger sample size and longer supplementation duration.

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