Transcranial Direct Current Stimulation of the Temporoparietal Junction in Autism Spectrum Disorder: Results of a Phase-IIa Randomized, Double-Blind, Sham-Controlled Feasibility Study.

This study tested a brain stimulation technique called tDCS on 24 autistic teens to see if it could improve social skills. The treatment was safe with no serious side effects, but didn't show clear benefits for social abilities compared to fake stimulation. Some improvements were seen in repetitive behaviors and quality of life. Recruitment was challenging, but those who participated stayed in the study well.

This Phase-IIa randomized controlled trial investigated transcranial direct current stimulation (tDCS) targeting the temporoparietal junction in autistic youth aged 10-17 years. Twenty-four participants received either active tDCS or sham stimulation alongside computer-based social cognitive training over 10 sessions. While recruitment feasibility was low (11% of screened individuals participated), retention, adherence, and safety were excellent with no serious adverse events. The primary outcome of social responsiveness showed no immediate post-intervention differences between groups, though sham showed a trend toward better outcomes at 4-week follow-up.

Secondary outcomes suggested potential benefits for compulsive behaviors and quality of life with tDCS. The mixed results indicate both positive and potentially negative effects of tDCS that may depend on stimulation parameters.

While tDCS appears safe in autistic youth, current evidence doesn't support its use for improving social responsiveness. The low recruitment feasibility highlights implementation challenges. Potential benefits for repetitive behaviors warrant further investigation with larger samples and optimized stimulation parameters before clinical application.

Very small sample size (N=24) limits statistical power. Low recruitment rate raises questions about generalizability. Mixed results with potential negative effects at follow-up require cautious interpretation. Short-term follow-up period limits understanding of sustained effects.

Activation of the temporoparietal junction (TPJ) is reduced in autism spectrum disorder (ASD) during social cognitive tasks. Therefore, anodal transcranial direct current stimulation (tDCS) of the TPJ may enhance social cognitive abilities in autistic individuals. In a multicenter, randomized, sham-controlled, double-blind parallel-group Phase-IIa trial, we investigated feasibility, safety, and effect sizes of 10 sessions of anodal tDCS of the bilateral TPJ at 2 mA as an add-on to computer-based social cognitive training in 10- to 17-year-old youth with autism. Feasibility of recruitment was low, with only 11% of screened individuals being randomized to tDCS (N = 12) or sham (N = 12).

In contrast, retention in the study, data collection, intervention adherence, and technical feasibility were mostly excellent. No serious adverse events occurred, and stimulation was well tolerated. There were no differences in the prespecified primary outcome social responsiveness between sham and tDCS immediately after the intervention (standardized estimated effect size [ES] = 0.098; 95%-confidence interval [95% CI] -1.043;1.240), but the sham group showed a trend for better social responsiveness at the 4 week follow-up (ES = 1.106; 95% CI -0.054; 2.270). Secondary outcomes including questionnaires and event-related potentials showed improved compulsive behavior and quality of life by tDCS.

High technical feasibility, participant retention, and safety highlight the potential of tDCS in autism and may inform future improvements in the feasibility of recruitment. The differential pattern of effect estimates indicates positive, but also potential negative effects of tDCS, which may vary due to tDCS stimulation parameters. The trial was prospectively registered in the German Clinical Trials Register (Deutsches Register für klinische Studien, DRKS, DRKS00014732).