Xenon Therapy for Children With Autism Spectrum Disorder

Inclusion Criteria: * Aged 4-18 years, with no gender restriction. * Meeting the diagnostic criteria for Autism Spectrum Disorder (ASD) as specified in the Diagnostic and Statistical Manual of Mental Disorders (5th Edition) (DSM-5), with the diagnosis confirmed by assessment using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2). * The total T-score on the Social Responsiveness Scale, Second Edition (SRS-2) is ≥90. * No treatment such as neuromodulation (transcranial magnetic stimulation, transcranial electrical stimulation) has been received for at least 1 month prior to randomization. * For participants who have previously taken psychotropic medications prior to randomization, it is required that the medications have been discontinued for a minimum of 5 half-lives or 4 weeks, whichever is longer. * The participants and their legal guardians confirm that they will not add new or alter the existing established treatment regimens such as behavioral rehabilitation during the study period. * The legal guardians of the participants have a full understanding of the study content, participate voluntarily, and sign a written informed consent form. Exclusion Criteria: * Having other major neurological diseases (e.g., epilepsy, cerebral palsy), severe physical illnesses, or genetic syndromes. * Having severe auditory or visual impairments that prevent the completion of assessments with cooperation. * A history of anaphylaxis or adverse reactions to Xenon. * Currently participating in or having participated in other interventional clinical trials within the recent 3 months. * The investigator judges that there is any condition that may increase the risk to the participant or interfere with the conduct of the trial and the assessment of its results.