Transcranial Direct Current Stimulation in Children With Autism Spectrum Disorder

Background: Transcranial Direct Current Stimulation (tDCS) is a form of non-invasive brain stimulation that has aroused increased interests in the past decade. Not only that it is transient with little side-effects, and can be well-tolerated by children, it is also affordable and readily accessible, making it an appealing treatment option for autism spectrum disorder (ASD). Objective: (1) To assess the therapeutic effects of tDCS when combined with cognitive training for 10 consecutive weekdays on improving cognitive processing in children with ASD, relative to control group receiving sham-stimulation, and (2) to evaluate the associated neural mechanisms underlying the treatment effect of tDCS on children with ASD. Methods: To assess the therapeutic effects of tDCS, 90 adolescents with ASD (age 6-12 years) will be randomly assigned to active- (n=45), or sham- (n=45) tDCS groups. Twenty-minute sessions of tDCS stimulation to the left dorsolateral prefrontal cortex (DLPRC) will be provided on 10 consecutive weekdays, in conjunction with cognitive training exercises. Participants with a head circumference of less than 53 cm will receive 1.0 mA of stimulation, while those with a circumference of 53 cm or greater will receive 1.5 mA. EEG, fNIRS and neuropsychological tests will be administered before, immediately after, and 2 months after the series of tDCS sessions. Hypothesis: The investigators hypothesize that children with ASD who are randomly assigned to receive a montage of prefrontal tDCS, with cathode (inhibitory) placed over left DLPFC and anode (excitatory) over right supraorbital region) will evidence greater improvement in executive function (primary outcome) than children with ASD who are randomly assigned to receive sham-tDCS. In addition to testing the primary clinical outcome, stated above, in planned exploratory analyses, the investigators will also examine the effects of tDCS on secondary outcome measures of cognitive function, including information