Transcranial direct current stimulation (tDCS) in psychiatric disorders in early childhood (aged under 10 years): a systematic review.

Transcranial direct current stimulation (tDCS) remains experimental for many psychiatric disorders in adults. Particularly in childhood, there is limited research on the evidence for the efficacy and mechanisms of action of tDCS on the developing brain. The objective of this review is to identify published experimental studies to examine the efficacy and mechanisms of tDCS in children with psychiatric or developmental disorders in early (prepubertal) childhood (aged under 10 years). Included Studies should meet the following criteria: (1) experimental studies (no reviews, no case reports), (2) studies published in international peer-reviewed journals, (3) written in English, (4) conducted on children under 10 under years of age, (5) at enrolment with a psychiatric or developmental disorder.Eight studies were identified that fulfilled the specified criteria. All studies investigated effect on children with autism-spectrum-disorder (ASD). Anodal tDCS, mainly targeting the left dorsolateral prefrontal cortex (dlPFC), showed positive effects on the reduction of ASD symptoms. There has also been evidence that these stimulations are feasible, have good tolerability and are safe. tDCS was found to be safe and partially effective, but a long-term effect of tDCS and changes in connectivity during tDCS in autism has not been proven. Other developmental or psychiatric diseases were not investigated. This results in a lack of knowledge regarding the reactivity of the brain during the prepubertal period, which is a critical phase in the pathogenesis of neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD), ASD, Tourette's syndrome or dyslexia.