Transcranial direct current stimulation yields some positive effect in pediatric ADHD

Key takeaways:

• Transcranial direct current stimulation significantly improved interference control but not working memory accuracy.
• No serious adverse events were reported in the sham or treatment groups.

Prefrontal transcranial direct current stimulation induced small- to medium-sized clinical effects in cognitive and clinical metrics in youths with ADHD with no serious adverse effects, according to a study published in JAMA Network Open.

“In recent years, the benefit of noninvasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS), has been explored in ADHD,” Kerstin Krauel, PhD, of the department of child and adolescent psychiatry and psychotherapy at Otto von Guericke University Magdeburg in Germany, and colleagues wrote.

Although a meta-analysis has suggested some positive effect of tDCS in pediatric ADHD, rigorously controlled clinical trials investigating this technology are scarce. As such, Krauel and fellow researchers aimed to determine effect sizes of changes in cognitive and clinical metrics, as well as safety and tolerability, of multichannel tDCS among youths with ADHD.

In the sham-controlled, double-blind, parallel-group randomized E-StimADHD clinical trial, the researchers recruited 69 youths aged 10 to 18 years (median age, 13.3 years; 78% boys) with ADHD from five university hospitals in Portugal and Germany between September 2018 and August 2021. Eligible participants had an IQ of at least 80 and refrained from taking stimulant medication 2 weeks before and during the trial.

Participants were randomly assigned to one of two independent study arms and underwent 10 sessions of optimized multichannel anodal tDCS or sham stimulation (1 mA, 20 minutes) targeting the left dorsolateral prefrontal cortex (study A) or the right inferior frontal gyrus (study B).

During the sessions, the researchers assessed performance on a specific task related to cognition (study A, working memory assessed in the n-back task; study B, interference control assessed in the flanker task). These tasks were also assessed at baseline, at a postintervention visit and within 4 to 5 weeks after the last session.

The primary outcome was effect sizes of changes in accuracy for both target tasks after the intervention, with analyses based on the modified intention-to-treat set of 66 participants.

Compared with sham, results showed that verum stimulation of the left dorsolateral prefrontal cortex led to significantly lower working memory accuracy in study A (effect size, 0.43 [95% CI, 0.68 to 0.17]), while stimulation of the right inferior frontal gyrus significantly improved interference control (effect size, 0.3 [95% CI, 0.04-0.56]) in study B.

In both study arms, verum and sham groups demonstrated lower values on the ADHD rating scale for total symptoms at postintervention and follow-up visits vs. baseline, although no significant differences were observed between groups.

The researchers reported 87 adverse events in the sham group and 74 in the treatment group, none of which were serious. The most frequently reported adverse events were headache, nasopharyngitis and feeling of electric discharge.

“Our findings ... suggest that optimized multichannel anodal tDCS over the prefrontal cortex in unmedicated youths with ADHD was safe and well tolerated in the observed period with our parameter settings and could induce small- to medium-sized effects in cognitive and clinical measures,” Krauel and colleagues wrote.