Anodal tDCS over the left DLPFC improved working memory and reduces symptoms in children with ADHD

Anodal transcranial direct current stimulation (tDCS) of the prefrontal cortex has repeatedly been shown to improve working memory. As patients with attention deficit hyperactivity disorder (ADHD) are characterized by both underactivation of the prefrontal cortex and deficits in working memory that correlate with clinical symptoms, it is hypothesized that the modulation of prefrontal activity with tDCS in patients with ADHD increases performance in working memory and reduces symptoms of ADHD. In a randomized, double-blinded, sham-controlled study, 1mA anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC) was applied on 5 consecutive days. Anodal tDCS caused a significant reduction in clinical symptoms of inattention and impulsivity in children with ADHD compared to sham stimulation. The clinical effects were supported by a significant reduction in inattention and hyperactivity in a standardized working memory test (QbTest). The described effects were more pronounced 7 days after the end of stimulation, a fact which emphasizes the long-lasting clinical and neuropsychological changes after tDCS. Moreover, the clinical and neuropsychological changes correlated with activation of neuronal networks of working memory and executive control following tDCS as revealed by functional MRI. This study highlights the potential of anodal tDCS of the left DLPFC as a form of treatment in patients with ADHD.