The Impact of Attention Deficit-hyperactivity Disorder Symptom Severity on the Effectiveness of Transcranial Direct Current Stimulation (tDCS) on Inhibitory Control

The present study aimed to assess the impact of transcranial direct current stimulation (tDCS) on different domains of inhibitory control in children with mild or severe ADHD symptoms. Twenty-four children with ADHD, in two groups with severe and mild symptoms, received anodal or sham tDCS over the right dorsolateral prefrontal cortex (dlPFC) during performing inhibitory control tasks. A significant main effect of stimulation condition was found that was limited to the circle tracing task, and the incongruent condition of the flanker task. Moreover, the main effects of stimulation condition and group were non-significant, but their interaction was significant for No-Go accuracy. The results suggest that the right dlPFC has a crucial role in ongoing inhibition in children with ADHD, and that tDCS has a partially symptom severity-dependent effect on inhibitory control. These findings are discussed in connection with severity-dependent psychopathology.