Apply tACS to Alleviate Anxiety Symptoms

Eligibility Criteria

• * Meet SCID-5/MINI KID criteria for one of the above-mentioned anxiety disorders.
• * Subject, or legally acceptable representative (LAR), is able to read, understand, and provide written informed consent and assent, as applicable.
• * Subjects requiring an LAR will have an identified caregiver who meets the following criteria: Able to reliably report and communicate on the subject's level of functioning and either lives with the subject or sees the subject on average for ≥ 3 hours/day ≥ 4 days/week, or receives reports from a caregiver, such as an aide, who meets this criteria, and in the investigator's opinion - the extent of contact is sufficient to provide meaningful assessment of changes in subject behavior and function over time
• * Able to be compliant with all study procedures
• * Age range: 5 years of age or older
• * Stable medications for non-excluded concurrent medical conditions for eight weeks prior to randomization
• * If receiving psychotherapy, participants must have started psychotherapy at least 2 months prior to randomization
• * Health: Physically acceptable for the study with no expected medical conditions likely to occur during or immediately after the study, as confirmed by medical history
• * Clinical laboratory values of TSH and T4, within 90 days from randomization must be within normal limits or judged not clinically related by the physician sub-investigator or PI to the subject's cognitive impairment if abnormalities are present.
• 1. Neurodegenerative disease
• 2. Epilepsy
• 3. Intellectual Disability
• 4. Pregnancy or lactation
• 5. Convexity skull defects
• 6. Raised intracranial pressure
• 7. Intracranial electrodes
• 8. Vascular clips or shunts in the brain
• 9. Cardiac pacemakers or other implanted biomedical devices
• 10. An active medical disorder that could explain, in the opinion of the PI or by medical history, the anxiety disorder.
• 11. Had an abrupt and significant change in functioning within 3 months of randomization.
• 12. Meets criteria for any substance use addiction as defined by DSM-5/SCID-5 CV.
• 13. Active alcoholism as defined by 3 or more bottles of beer or glasses of wine or 2 hard liquor drinks per day/night 3 or \> times per week at any time within the past 12 weeks of screening or any other addiction to non-prescription substances.
• 14. Schizophrenia spectrum disorders and bipolar spectrum disorders.
• 15. Active suicidal tendency (evaluated by Columbia-Suicide Severity Rating Scale \[C-SSRS\], traditional version). Note: If the BDI or CDS of the participants significantly increase, the CSSRS will be repeated.
• 16. Unstable medical condition (including expected medication change/titration).
• 17. Premenstrual dysphoric disorder.
• 18. Factious/malingering disorder and any patients applying for disability warranty.
• 19. Somatoform disorders subtypes: conversion and hypochondriasis.