Transcranial direct current stimulation on social communication among children and adolescents with autism spectrum disorder: a systematic review and meta-analysis

BACKGROUND: Transcranial direct current stimulation (tDCS) has gained attention as a potential intervention to improve social cognition in children with autism spectrum disorder (ASD). However, its effects across social domains and the influence of stimulation parameters remain unclear. This systematic review and meta-analysis evaluate the effectiveness of tDCS in enhancing social functioning in children with ASD, focusing on emotion recognition, theory of mind (ToM), and social responsiveness. METHODS: A comprehensive search identified randomized controlled trials (RCTs) investigating tDCS effects on social cognition in children with ASD. Studies were assessed for effect sizes and statistical significance. A meta-analysis pooled results, and moderators of tDCS effectiveness were examined. RESULTS: Screening 14 studies revealed that anodal tDCS applied to the left dorsolateral prefrontal cortex (DLPFC) produced the most consistent improvements in emotion recognition, ToM, and social responsiveness. However, results varied, with some studies reporting improvements, while others showed no substantial effects. Dual-stimulation or cathodal stimulation yielded mixed outcomes. Evidence was limited by small sample sizes, risk of bias, and variability in stimulation parameters. CONCLUSIONS: Anodal tDCS over the left DLPFC shows promise for improving social cognition in ASD. Larger controlled trials are needed to determine the effectiveness of combining tDCS with social skills training.