Apply tACS to Alleviate Anxiety Symptoms

Inclusion 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, andprovide written informed consent and assent, as applicable.
• Subjects requiring an LAR will have an identified caregiver who meets the followingcriteria: Able to reliably report and communicate on the subject's level offunctioning and either lives with the subject or sees the subject on average for ≥ 3hours/day ≥ 4 days/week, or receives reports from a caregiver, such as an aide, whomeets this criteria, and in the investigator's opinion - the extent of contact issufficient to provide meaningful assessment of changes in subject behavior andfunction 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 weeksprior to randomization
• If receiving psychotherapy, participants must have started psychotherapy at least 2months prior to randomization
• Health: Physically acceptable for the study with no expected medical conditions likelyto 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 bewithin normal limits or judged not clinically related by the physiciansub-investigator or PI to the subject's cognitive impairment if abnormalities arepresent.

Exclusion Criteria:

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 medicalhistory, 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 hardliquor drinks per day/night 3 or > times per week at any time within the past 12 weeksof 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 participantssignificantly 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.