Transcranial Alternating Current Stimulation (tACS) for the Treatment of Anxiety in Veterans: An Open-Label Pilot Study

Inclusion Criteria: * Veteran of the U.S. military * English-speaking and provides signed informed consent and HIPAA * Adults ≤70 years of age * Past week's GAD-7 of ≥10 which represents at least moderate level of anxiety * If applicable, antidepressants may be continued if taking the concomitant medication for ≥8 weeks and at stable doses for ≥4 weeks * Participants of child-bearing potential must have negative pregnancy test at entry and must agree to adhere to a medically acceptable method of birth control Exclusion Criteria: * Lifetime bipolar type I, schizophrenia spectrum, or other psychotic disorders based on VA medical records * Current sedative-hypnotic, stimulant, inhalant and/or opioid use disorder within the past 6 months based on VA medical records and clinical interview * Diagnosis of moderate to severe alcohol and/or cannabis use disorder within past 6 months based on VA medical records and clinical interview * History of severe traumatic brain injury (TBI), defined by Ohio State University TBI Identification Method * Dementia or related progressive neurocognitive disorder as per the medical record * Use of prohibited medications (see list above) in the prior 2 weeks * Increased risk of suicide that necessitates inpatient treatment, suicidal ideation/behavior endorsed on 6-item Columbia Suicide Severity Rating Scale screening questionnaire (yes" to question 4 or 5; or yes to # 6 as current), and/or suicidal behavior within past 90 days. * Treatment with electroconvulsive therapy, vagus nerve stimulation, or transcranial magnetic stimulation within the past 6 months * Implanted central nervous system devices (e.g. deep brain stimulation) * Implanted cardiac pacemaker * Trigeminal neuralgia that is currently symptomatic * Treatment with evidence-based psychotherapy (EBP) for anxiety, depression or PTSD in the past 14 days. If receiving EBP therapy, he/she should complete EBP prior to entering study. Veterans currently engaged in non-EBP, e.g., supportive counseling or skills group therapies, may continue in these if they have been in this treatment for at least 4 weeks prior to baseline assessments. * Pregnancy during treatment * Clinically significant medical/surgical illness that would contraindicate use of tACS, e.g. unstable cardiac condition, those who fear electrical stimulation, presence of skin irritation or abrasions around either electrode site, or who have shrapnel fragments near either electrode site. * Litigating for disability income for a mental disorder outside the VA compensation and pension process