Effects of L-theanine-caffeine combination on selective attention among adolescents with attention-deficit hyperactivity disorder: a double-blind, placebo-controlled, crossover study.
Gayani S Nawarathna, Dewasmika I Ariyasinghe, Nilantha Balasooriya et al.
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In 30 seconds
This double-blind, placebo-controlled, counterbalanced crossover trial examined acute effects of L-theanine plus caffeine, compared with methylphenidate and placebo, on selective attention in 21 adolescents with ADHD aged 10–19 years. Participants completed a computerized attention task before and 50 minutes after each treatment. Compared with placebo, the combination reduced false alarms (P = 0.038), as did methylphenidate (P = 0.035); neither treatment significantly changed hits or discrimination sensitivity. Only methylphenidate significantly improved reaction time versus placebo, by a mean difference of 43.89 ms (P = 0.018). Both active treatments altered P3b measures in the direction of greater amplitude and shorter latency.
Key findings
- L-theanine-caffeine and methylphenidate each reduced false alarms versus placebo (P = 0.038 and P = 0.035, respectively).
- Only methylphenidate improved reaction time versus placebo (mean difference = 43.89 ms, P = 0.018).
- Hits and target-distractor discrimination sensitivity did not differ significantly between treatments (P > 0.05).
- Both active treatments increased P3b amplitudes and decreased latencies versus placebo (P < 0.05).
Why it matters
The findings suggest that an acute L-theanine-caffeine combination may affect some aspects of selective attention in adolescents with ADHD, including false alarms and task-related neural responses. However, it did not show the reaction-time improvement observed with methylphenidate, and the study does not establish longer-term benefit. These results add preliminary evidence about a possible adjunct, rather than demonstrating an alternative to established treatment.
What to keep in mind
The trial included only 21 adolescents and assessed acute effects during a computerized task, so it does not establish longer-term effects or benefits in everyday functioning.