tDCS improves core symptoms and social communication in children and adolescents with autism spectrum disorders

OBJECTIVE: This study aimed at investigating the effectiveness of transcranial direct current stimulation (tDCS) in improving autism spectrum disorder (ASD)-related behavioral symptoms in children and adolescents. METHODS: Randomized placebo-controlled trials (RCTs) recruiting children/adolescents were identified from major databases using the keywords "tDCS" and "ASD". Outcomes included improvement in ASD-related overall/core symptoms and treatment acceptability. Effect sizes of continuous and categorical data were expressed as standardized mean difference (SMD) and odds ratios (ORs), respectively, with 95% confidence intervals. RESULTS: Meta-analysis of nine RCTs (278 participants, mean age = 8.1) showed improvement in overall behavioral symptoms, social function, and communication in the tDCS group compared with sham-controls [SMD = -0.50, p < 0.01; SMD = -0.40, p = 0.02 (seven studies) and SMD = -0.34, p = 0.04 (six studies), respectively] without difference in symptoms of restricted and repetitive behaviors (SMD = -0.36, p = 0.06). Subgroup analysis revealed greater improvement in studies enrolling only children than those that also recruited adolescents (SMD = -0.70 vs. -0.06, respectively, p = 0.03). No difference was noted in treatment acceptability (i.e., the number of participants withdrawing from a study) between the tDCS and sham-controlled groups. CONCLUSIONS: Our study supported tDCS use for improving overall behavioral symptoms of ASD in children and adolescents, mainly those pertinent to socio-communication, with fair treatment acceptability.