A meta-analysis is a method to summarize the effects of multiple studies on the same topic (read more about meta-analyses in the Neuroscience Methods section). With tDCS activity in the brain can be changed, which can lead to a small change in behavior (read more about tDCS in the Neuroscience Methods section). Here we summarized 10 international and independent studies on the effects of tDCS in children with attention-deficity hyperactivity disorder (ADHD). 

On symptom of ADHD is that children are often restless and can't constrain their behavior. Constraining yourself is also called inhibition. Therefore, previous studies have looked at whether tDCS improves the inhibition of children with ADHD. 

Another symptom of ADHD is their they have difficulty to focus and therefore lack attention. This lack of attention leads to deficits in working memory, which is the ability to shortly remember a number of words, numbers, letters, and so on.

Evidence from 10 international studies showed that tDCS in children with ADHD can improve their inhibition. This was the case when a region was stimulated called the dorsolateral prefrontal cortex. 

Overall, no effect was found of tDCS on working memory of children with ADHD. However, in a sub-analysis we found that tDCS may improve the response speed in such tasks.

In sum, it seems that tDCS can have beneficial effects in children with ADHD. This may indicate the potential for tDCS as an alternative to symptom suppression with medication. It should, however, be noted that the observed effects were small. So, more research is needed to optimize the effects of tDCS.