The effects of rTMS and tDCS on repetitive/stereotypical behaviors, cognitive/executive functions in intellectually capable children and young adults with autism spectrum disorder: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE: This study aims to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) on repetitive/stereotypical behaviors and cognitive/executive functions in children and young adults with intellectually capable autism spectrum disorder (IC-ASD). METHODS: Literature searches across PubMed, Web of Science, Cochrane Library, Embase, and Scopus were performed to identify randomized controlled trials (RCTs) evaluating the efficacy of rTMS and tDCS in children and young adults with IC-ASD. The search encompassed articles published up to April 25, 2025. The standardized mean difference (SMD) with 95% confidence intervals (CI) was calculated and pooled. Sensitivity and subgroup analyses were conducted to assess potential sources of heterogeneity and refine the robustness of the findings. RESULTS: This meta-analysis included 18 RCTs involving 813 participants. Compared with sham interventions, tDCS demonstrated significant improvements in social communication, repetitive and stereotypical behaviors, cognitive and executive functions among individuals with IC-ASD (e.g., Social Responsiveness Scale: SMD = -0.48; 95% CI: -0.75 to -0.22; p<0.01). Similarly, rTMS improved social communication, repetitive and abnormal behaviors (Social Responsiveness Scale: SMD = -0.21; 95% CI: -0.42 to -0.00; p<0.05; Repetitive Behavior Scale-Revised: SMD = -0.62; 95% CI: -1.17 to -0.07; p=0.04; Aberrant Behavior Checklist: SMD = -0.53; 95% CI: -0.79 to -0.26; p<0.01). No significant heterogeneity was observed across studies.CONCLUSION: tDCS and rTMS may enhance cognitive and executive functions and reduce repetitive behaviors in children and young adults with IC-ASD. However, these findings require careful interpretation due to the limited high-quality studies and variability in treatment protocols. Future research should prioritize the development of standardized protocols to address inconsistencies in stimulation parameters (including frequency, intensity, and duration) and core outcome sets. Additionally, larger-scale, rigorously blinded multi-center RCTs are necessary to accurately evaluate the clinical efficacy and applicability of these neuromodulation techniques in these populations.