Thus, increased reactivity of DMN is an established phenomenon contributing to impaired sustained attention and inhibitory control among individuals with ADHD. In another study, high level of impulsivity was associated with decreased reactivity of both anterior and posterior DMN 12. ADHD children while engaged in a sustained attention task revealed that children with ADHD show increased task-related reactivity of the posterior DMN 11. Comparison of fMRI brain reactivity neurotypical vs. Multiple functional MRI (fMRI) studies have established that a functional brain network, known as the default mode network (DMN), which includes the medial prefrontal cortex (anterior node of DMN), posterior cingulate cortex and precuneus (posterior node of DMN), shows increased reactivity during mind wandering even in neurotypical individuals 10. Increased mind wandering is negatively correlated with ADHD symptom severity 8, 9. Impaired sustained attention and inhibitory control in patients with ADHD is associated with increased task-associated mind wandering 8, 9, 10, 11, 12. Thus, ADHD seems to affect multiple cognitive domains and these deficits may be contributing to academic underachievement that is associated with ADHD 7. In addition to impairments in sustained attention and impulse control, children with ADHD may also experience deficits in multiple executive functions including planning, visual and verbal working memory, and task-switching 2. This repeatedly observed phenomenon led to the theory that lack of inhibitory control may be the primary cognitive deficit in ADHD 6. Similarly, multiple studies and meta-analyses have shown that impulse control is impaired in ADHD 5. Impaired sustained attention, operationally defined as the inability to maintain voluntary focus on events that occur infrequently for a sustained period of time, is a major and extensively studied cognitive deficit associated with ADHD 2, 3, 4. l-Theanine–caffeine combination may be a potential therapeutic option for ADHD-associated impairments in sustained attention, inhibitory control and overall cognitive performance.Īttention deficit hyperactivity disorder (ADHD) is characterized by impaired attention, hyperactivity and increased impulsivity 1. l-Theanine–caffeine combination was associated with decreased task-related reactivity of a brain network associated with mind wandering (i.e. 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). increased Stop-signal reaction time p = 0.031 and p = 0.053 respectively). Caffeine worsened and l-theanine had a trend of worsening inhibitory control (i.e. l-Theanine improved total cognition composite in NIH Cognition Toolbox (p = 0.040) vs. placebo effects were examined in multi-level mixed-effects models. NIH Cognition Toolbox was administered ~ 2 h post-dose. Functional magnetic resonance imaging (fMRI) was performed during a Go/NoGo task and a Stop-signal task ~ 1 h post-dose. 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. 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).
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