Combined Transcranial Direct Current Stimulation and Selective Motor Training Enhances Balance in Children With Autism Spectrum Disorder

Abstract

Previous studies have shown that transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) can facilitate the consolidation of motor skills in people who are typically developed, especially when tDCS is combined with goal-oriented exercises. Yet, the effect of tDCS on the motor skills of children with autism spectrum disorder is unknown. This study sought to investigate the effects of combined anodal tDCS and selective motor training on balance among 18 children with autism spectrum disorder (aged 6–14 years) who we randomly assigned to equal-sized experimental and control groups. The experimental group practiced motor training to improve balance after receiving 1.5 mA anodal tDCS over the left M1 for 20 minutes before each of 10 motor training sessions. The control (sham) group underwent a similar protocol with identical motor training, but tDCS was only artificially administered to them. We evaluated participants’ balance at baseline and after training. Data analysis showed that both anodal tDCS plus motor skill training and motor skill training with sham tDCS had significant positive impacts on balance, but tDCS participants who received both actual tDCS and motor skill training performed significantly better than those who received SHAM tDCS and motor skill training. These preliminary findings suggest that tDCS may enhance motor skill training for children with autism spectrum disorder, but replications with larger samples involving participants with varying levels of autistic symptoms and varied tDCS stimulation polarity are needed to affirm the practical use of this noninvasive brain stimulation.

Exercise-Based Interventions Aimed at Improving Balance in Children with Autism Spectrum Disorder: A Meta-Analysis

“…Among the many studies of intervention programs/training protocols aimed at improving balance in individuals with ASD, there have been interventions that can be classified as exercise- or sport-based, such as taekwondo, skating, karate, and aquatic exercise (Ansari et al, 2020; Casey et al, 2015; Cheldavi et al, 2014; Kim et al, 2016), videogame-based interventions (Fang et al, 2018; Travers et al, 2018), and sensory-based methods (Case–Smith et al, 2014; Pfeiffer et al, 2011). Some interventions have used new neuroscience technology such as transcranial direct current stimulation to improve balance in children with ASD (Mahmoodifar & Sotoodeh, 2019). Despite this variety among ASD interventions targeting balance, exercise-based interventions have been most common, and previous studies have shown their positive effects on the motor skills of children with ASD, including bilateral coordination, running speed, agility, and balance (Yin & Yin, 2019).…”

A systematic review of randomized controlled trials on efficacy and safety of transcranial direct current stimulation in major neurodevelopmental disorders: ADHD, autism, and dyslexia

“…Cathodal stimulation over the left dlPFC is also applied in ASD (GÃmez et al., 2017 ) and in two open‐label studies that were not included in this review. Two recent studies also reported improving effects of frontocerebellar tDCS (i.e., anodal left dlPFC, cathodal right cerebellar tDCS) on behavioral symptoms (Toscano et al., 2019 ), and anodal stimulation over the primary motor cortex on motor skill training in children with ASD (Mahmoodifar & Sotoodeh, 2020 ). Of 11 included studies, only 1 study targeted right TPJ and vmPFC, two key regions in the theory of mind in ASD, and found that anodal vmPFC, but not r‐TPJ tDCS, significantly improved ToM in children with ASD (Salehinejad et al., 2021 ).…”

“…and here, anodal tDCS over the left dlPFC (in 7 out of 11 studies) (Amatachaya et al, 2014;Amatachaya et al, 2015;Han et al, 2022;Kang et al, 2018;Qiu et al, 2021;Sun et al, 2022;Toscano et al, 2019) was the most often applied protocol in ASD. In one study (Hadoush et al, 2020) on behavioral symptoms (Toscano et al, 2019), and anodal stimulation over the primary motor cortex on motor skill training in children with ASD (Mahmoodifar & Sotoodeh, 2020). Of 11 included studies, only 1 study targeted right TPJ and vmPFC, two key regions in the theory of mind in ASD, and found that anodal vmPFC, but not r-TPJ tDCS, significantly improved ToM in children with ASD .…”

A systematic review of randomized controlled trials on efficacy and safety of transcranial direct current stimulation in major neurodevelopmental disorders: ADHD, autism, and dyslexia

“…Cathodal stimulation over the left dlPFC is also applied in ASD 52 and in two open-label studies that were not included in this review. Two recent studies also reported improving effects of frontocerebellar tDCS (i.e., anodal left dlPFC, cathodal right cerebellar tDCS) on behavioral symptoms 55 , and anodal stimulation over the primary motor cortex on motor skill training in children with ASD 75 . Of 11 included studies, only 1 study targeted right TPJ and vmPFC, two key regions in the theory of mind in ASD, and found that anodal vmPFC but not r-TPJ tDCS significantly improved ToM in children with ASD 76 .…”

“…Of 11 included studies, only 1 study targeted right TPJ and vmPFC, two key regions in the theory of mind in ASD, and found that anodal vmPFC but not r-TPJ tDCS significantly improved ToM in children with ASD 76 . 9 of 11 studies had repeated protocols in which tDCS was applied on consecutive days for 10, 12, 15, or 20 sessions [52][53][54][55]70,71,[73][74][75] . All of these studies reported significant improvement of their outcome variables (mostly ASD symptoms) and repeated daily sessions…”