Various methods have been attempted to effectively ameliorate psychiatric and neurological conditions in children and adults. One of the attractive ideas is to develop interventions to create a lasting, rather than only an immediate, effect. Neurostimulation has been shown to yield long-term effect when combined with cognitive training in healthy young adults. We examined whether such approach could benefit children with attention deficit hyperactivity disorder (ADHD), the most common neurodevelopmental disorder in childhood. We used a randomized double-blind active-controlled crossover study of 19 unmedicated children (aged 7-12 years old) with attention deficit hyperactivity disorder, who received either transcranial direct current stimulation or random noise stimulation while completing five-day executive functions training, which includes working memory, cognitive flexibility, and inhibition tasks. Both stimulation protocols have previously shown potential for inducing lasting benefits in adults, while transcranial direct current stimulation was examined in multiple attention deficit hyperactivity disorder studies and has been highlighted as a promising method for treating neuropsychological deficits. For our primary outcome, transcranial random noise stimulation yielded a clinical improvement as indicated by the reduced attention deficit hyperactivity disorder rating scale score from baseline, and in comparison to the changes observed in transcranial direct current stimulation. Moreover, the effect of brain stimulation one week after completion of treatment yielded further improvement, suggesting a neuroplasticity-related effect. Finally, transcranial random noise stimulation improved working memory compared to transcranial direct current stimulation, and a larger transcranial random noise stimulation effect on attention deficit hyperactivity disorder rating scale was predicted for those patients who showed the greatest improvement in working memory. Our results provide a promising direction toward a novel intervention in attention deficit hyperactivity disorder, which is shown to have a lasting effect via the modulating of neuroplasticity, rather than a merely immediate effect as was shown for in previous medical interventions.
