Effectiveness of Transcranial Direct Current Stimulation (tDCS) in Reducing Anxiety and Aggression in 6- to 10-Year-Old Boys With High-Functioning Autism Spectrum Disorder

Tanaz Yousefi; Saqqa Afrakhteh; Mehran Azadi

Authors

Tanaz Yousefi Ph.D. Candidate in Psychology, Department of Psychology, NT.C., Islamic Azad University, Tehran, Iran Author https://orcid.org/0009-0005-5776-5340
Saqqa Afrakhteh Assistant Professor, Department of Psychology, NT.C., Islamic Azad University, Tehran, Iran Corresponding Author https://orcid.org/0009-0004-7817-3195
Mehran Azadi Assistant Professor, Department of Psychology, NT.C., Islamic Azad University, Tehran, Iran Author https://orcid.org/0000-0003-0605-5582

Keywords:

Transcranial Direct Current Stimulation, tDCS, Autism Spectrum Disorder, Anxiety, Aggression, High-Functioning Autism

Abstract

This study aimed to determine the effectiveness of transcranial direct current stimulation (tDCS) in reducing anxiety and aggression in 6- to 10-year-old boys with high-functioning autism spectrum disorder. This quasi-experimental study employed a pretest–posttest–follow-up design with an active intervention group and a sham-control group. The statistical population consisted of 6- to 10-year-old boys with high-functioning autism spectrum disorder attending specialized autism treatment and rehabilitation centers in Tehran, Iran, from late October 2025 to January 2026. Thirty eligible children were selected through purposive sampling and randomly assigned to an active tDCS group (n = 15) or a sham-control group (n = 15). The experimental group received 10 individual tDCS sessions over four weeks, with 1 mA anodal stimulation applied over the left dorsolateral prefrontal cortex for 20 minutes per session. In the sham condition, stimulation was discontinued after approximately 30 seconds. Anxiety was assessed using the Anxiety Scale for Children with Autism Spectrum Disorder–Parent Version, and aggression was measured using the Children’s Scale of Hostility and Aggression: Reactive/Proactive. Assessments were conducted at pretest, posttest, and one-month follow-up. Data were analyzed using repeated-measures analysis of variance and Bonferroni-adjusted pairwise comparisons in SPSS version 26. Repeated-measures analysis showed significant time × group interactions for anxiety, F(2, 56) = 61.90, p < .001, partial η² = .618, and aggression, F = 10.61, p < .001, partial η² = .342. Significant between-group effects were also observed for anxiety, F(1, 28) = 7.73, p = .005, and aggression, F(1, 28) = 4.95, p = .036. Bonferroni comparisons indicated significant pretest-to-posttest and pretest-to-follow-up reductions in both anxiety and aggression, whereas posttest-to-follow-up differences were nonsignificant, indicating maintenance of treatment effects. The findings indicate that repeated prefrontal tDCS can significantly reduce anxiety and aggression in boys with high-functioning autism spectrum disorder, with improvements remaining stable one month after treatment.

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