This is a prospective, single-center, single-arm, investigator-initiated exploratory clinical trial aimed at evaluating the safety and exploring the efficacy of a medical electromagnetic stimulator delivering low-frequency repetitive transcranial magnetic stimulation (rTMS) in children and adolescents with Autism Spectrum Disorder (ASD). ASD is a neurodevelopmental disorder characterized by deficits in social interaction and communication and restricted, repetitive behaviors. Despite increasing prevalence, effective treatment options remain limited, and the demand for non-invasive, safe interventions continues to grow.

In this study, a total of 18 participants aged 3 to 17 years with a clinical diagnosis of ASD will be enrolled. Participants will receive rTMS using a medically approved electromagnetic stimulator applied to the dorsolateral prefrontal cortex (DLPFC) - five sessions per week for two consecutive weeks (total of 10 sessions). The first 5 sessions will target the left DLPFC, and the remaining 5 will target the right DLPFC. Each session includes 18 trains of 10-second stimulations at 1Hz frequency with 20-second inter-train intervals. The stimulation intensity is set at 90% of the resting motor threshold (rMT), determined individually using motor evoked potential testing.

The primary objective of this trial is to assess the safety of low-frequency rTMS in this population, with adverse events such as seizures, headaches, dizziness, and mood changes monitored throughout the trial. Vital signs will also be checked before and after each session. Secondary objectives include exploratory evaluation of rTMS effects on sensory processing (SP), social communication (SCQ), autism severity (K-CARS), behavioral symptoms (CBCL), brain activity changes (fNIRS), and electrophysiological responses (EEG), assessed at baseline, immediately after intervention, and at 1- and 3-month follow-ups.

All participants will undergo baseline assessments including EEG, SP, SCQ, K-CARS, CBCL, fNIRS, and vital signs. These measures will be repeated after the final rTMS session, and again at 1 and 3 months post-intervention. The trial will be conducted at CHA Bundang Medical Center, led by Principal Investigator Professor Minyoung Kim, Department of Rehabilitation Medicine.

This exploratory study is designed to provide preliminary evidence for the safety of low-frequency rTMS in ASD and to gather pilot data on its potential therapeutic effects, which may support future randomized controlled trials and clinical applications.

Inclusion Criteria:

1. Aged between 3 and 17 years at the time of enrollment
2. Clinically diagnosed with Autism Spectrum Disorder (ASD), including assessment using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2)
3. Currently receiving outpatient care for ASD at the Department of Rehabilitation Medicine, CHA Bundang Medical Center
4. The participant and their legal guardian have been fully informed of the study and have voluntarily provided written informed consent

Exclusion Criteria:

1. Diagnosed with a major neurological condition other than ASD

2. Epileptiform discharges detected on EEG screening requiring initiation or adjustment of antiepileptic medication

3. Diagnosed with other psychiatric disorders, such as schizophrenia or major depressive disorder

4. History of traumatic brain injury, brain tumor, or other significant brain conditions

5. Deemed unsuitable for participation by the principal investigator

6. Currently participating in another interventional clinical trial, or has participated in one within the past 30 days (excluding observational studies)

7. Any of the following contraindications to rTMS:

   • Implanted electronic medical devices (e.g., pacemaker)
   • Presence of metal implants in the skull
   • Skin lesions at the stimulation site
   • History of epilepsy
   • Cervical spine pain or musculoskeletal disorders
   • Pregnancy or currently breastfeeding