Effects of l -theanine–caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT

摘要

We examined the acute effects of l-theanine, caffeine and their combination on sustained attention, inhibitory control and overall cognition in boys with attention deficit hyperactivity disorder (ADHD). l-Theanine (2.5?mg/kg), caffeine (2.0?mg/kg), their combination and a placebo were administered in a randomized four-way repeated-measures crossover with washout, to five boys (8–15?years) with ADHD. Functional magnetic resonance imaging (fMRI) was performed during a Go/NoGo task and a Stop-signal task?~?1?h post-dose. NIH Cognition Toolbox was administered?~?2?h post-dose. Treatment vs. placebo effects were examined in multi-level mixed-effects models. l-Theanine improved total cognition composite in NIH Cognition Toolbox (p?=?0.040) vs. placebo. Caffeine worsened and l-theanine had a trend of worsening inhibitory control (i.e. increased Stop-signal reaction time; p?=?0.031 and p?=?0.053 respectively). l-Theanine–caffeine combination improved total cognition composite (p?=?0.041), d-prime in the Go/NoGo task (p?=?0.033) and showed a trend of improvement of inhibitory control (p?=?0.080). l-Theanine–caffeine combination was associated with decreased task-related reactivity of a brain network associated with mind wandering (i.e. default mode network). l-Theanine–caffeine combination may be a potential therapeutic option for ADHD-associated impairments in sustained attention, inhibitory control and overall cognitive performance.