Behavioral Effects of Transcranial Direct Current Stimulation on Motor and Language Planning in Minimally Verbal Children with Autism Spectrum Disorder (ASD): Feasibility, Limitations and Future Directions

Abstract

Autism Spectrum Disorder (ASD) affects millions of individuals in the United States, with 1 in 68 American children currently diagnosed. Individuals with ASD exhibit profound planning deficits, in both motor and language. This study considers how anodal transcranial direct current stimulation (tDCS)-which passes a weak electrical current between two electrodes and facilitates neuronal activity-might be used as a novel rehabilitation technique for children with ASD. Anodal tDCS has been shown to improve motor planning in neurotypical individuals and has been implicated in improving grammar acquisition in children with ASD. Three minimally verbal children with diagnosed or suspected ASD received a low current intensity of tDCS (0.4 mA) for a long duration (90 minutes). Children completed reaction time, balance, and fine motor skill planning tasks before and after receiving tDCS. During stimulation, participants engaged in combined speech/occupational therapy activities. Data collection is limited because of the difficulties in testing this population. However, observations from work have indicated that tDCS is feasible in children with ASD, and tDCS is potentially capable of inducing long-lasting improvements in motor planning and grammar use in children with ASD.

Single-arm, open-label, dose escalation phase I study to evaluate the safety and feasibility of transcranial direct current stimulation with electroencephalography biomarkers in paediatric disorders of consciousness: a study protocol

“…This study will provide an initial structure to optimise dosage in neurologically compromised paediatric populations. Research has taken a cautionary approach to tDCS dosage in such populations; a study in autism with minimally verbal children used lower dosages and increased duration to maximise tolerability 46. This study will use standard tDCS dosages in accordance with head circumferences of children to evaluate the appropriateness of this approach in medically fragile children.…”

Effects of Non-invasive Neurostimulation on Autism Spectrum Disorder: A Systematic Review

“…Eight studies exclusively utilized tDCS as the therapeutic tool [ 33 - 40 ], 23 studies utilized solely rTMS as the therapeutic tool [ 41 - 63 ], and one study used both rTMS and tDCS to evaluate their therapeutic effects on ASD [ 64 ]. Six of the included articles were case-reports [ 35 , 40 , 43 , 47 , 49 , 53 ], nine were non-controlled trials [ 36 , 37 , 41 , 46 , 55 , 57 , 61 , 62 , 64 ], and the remaining 17 were controlled trials [ 33 , 34 , 38 , 39 , 42 , 44 , 45 , 48 , 50 - 52 , 54 , 56 , 58 - 60 , 63 ]. Eleven of the controlled studies used a sham group as the control [ 33 , 34 , 38 , 39 , 42 , 48 , 50 - 52 , 54 , 63 ] and the remaining six compared neuromodulated patients with waitlist controls.…”

“…Figure 1 shows a schematic overview of the study selection process. Eight studies exclusively utilized tDCS as the therapeutic tool [33][34][35][36][37][38][39][40], 23 studies utilized solely rTMS as the therapeutic tool , and one study used both rTMS and tDCS to evaluate their therapeutic effects on ASD [64]. Six of the included articles were case-reports [35,40,43,47,49,53], nine were non-controlled trials [36,37,41,46,55,57,61,62,64], and the remaining 17 were controlled trials [33,34,38,39,42,44,45,48,[50][51][52]54,56,[58][59][60]63].…”

Repeated Sessions of Transcranial Direct Current Stimulation on Adolescents With Autism Spectrum Disorder: Study Protocol for a Randomized, Double-Blind, and Sham-Controlled Clinical Trial

“…Therefore, the current evidence is sparse and methodologically incomparable ( 79 ). Nevertheless, these studies point toward positive effects of tDCS in the treatment of ASD showing an improvement in ASD symptoms such as socialization, sensory awareness, repetitive behaviors, and behavioral problems ( 65 , 68 , 70 , 76 ) as well as in cognitive abilities often impaired in individuals with ASD ( 71 , 74 ). The available results not only provide indications for significant symptom reductions maintained for 6 months ( 68 ) but also emphasize the necessity of further research ( 70 , 79 ).…”