3.50 Effect of Anodal Transcranial Direct Current Stimulation (tDCS) for ADHD in Children and Adolescents: Systematic Review of RCTs

Underactivation of prefrontal cortex in ADHD correlates with its attention-related symptoms. Modulation of prefrontal activity with transcranial direct current stimulation (tDCS) is proposed to reduce inattention symptoms in ADHD. Longer lasting clinical and neuropsychological changes of this neuromodulation are presumed to be via potentiation of mediators of synaptic plasticity, including gamma-aminobutyric acid (GABA), glutamate, dopamine, and noradrenaline. The aim was to review short- and long-term efficacy and side effects of anodal tDCS at the left dorsolateral prefrontal cortex (DLPFC) in children and adolescents with diagnosed ADHD. Studies were included if they were: 1) randomized controlled trials published from 2014 to present; 2) assessed efficacy of anodal tDCS at 3) DLPFC in 4) children and adolescents with diagnosed ADHD. The scales used were: Vanderbilt ADHD Diagnostic Parent Rating Scale (VADPRS), Adverse Effects Questionnaire, ADHD rating scale (ADHD-RS), Quantified Behavioral (Qb) test, and the German ADHD Rating Scale, Fremdbeurteilungsbogen ADHS (FBB-ADHS). Improved test scores were used as a determinant of effective treatment. Using 6 electronic databases, 21 original studies were identified. After deleting duplicates, 17 unique studies were screened. Finally, 3 randomized controlled trials were included in the review. We extracted data for study demographics and efficacy outcomes. Overall, 59 ADHD patients with mean age 11.5 ± 4.5 years, were enrolled for trials. Participants were treated with direct anodal current ranging 0.75-1 milliamp for 2 to 12 sessions of 20 minutes, over a mean duration of 4 weeks, specifically targeted at DLPFC. Only 1 trial found a clinically significant improvement in inattention symptoms (p = .03), with more pronounced effects a week after end of stimulation (p = .05). One trial found no significant postintervention differences between the tDCS (p = .906) and sham groups. The third trial found transcranial random noise stimulation (tRNS) (p = .028) to be superior to tDCS. Clinically significant side effects included: itching/burning sensation of scalp (n = 8) and headaches (n = 4). tDCS can be an effective treatment for improving inattention symptoms in ADHD. However, evidence is limited for improvement in hyperactivity or cognitive performance. A larger sample size and a more prolonged exposure to tDCS is warranted to allow generalizability of findings.