Inclusion Criteria:
1. Age 7-17 years
2. Diagnosis of Autism Spectrum Disorder (ASD) confirmed by the study clinician using the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria and Social Communication Questionnaire (SCQ)
3. Diagnosis of social phobia, separation anxiety disorder, or generalized anxiety disorder of at least moderate severity based on the Anxiety and Related Disorders Interview Schedule (ADIS), 5-item Pediatric Anxiety Rating Scale (PARS) score ≥10, and Clinical Global Impression Severity subscale (CGI-S) ≥4
4. IQ ≥50 based on Stanford Binet, 5th Edition Abbreviated IQ test or the Kaufman Brief Intelligence Test, 2nd Edition (KBIT-2)
5. Stable medications for ≥30 days
6. English speaking
7. Ability to swallow buspirone capsules or liquid suspension
Exclusion Criteria:
1. Known diagnosis of a genetic syndrome associated with ASD (e.g. Fragile X syndrome, Angelman syndrome) based on parent report
2. Known cardiac arrythmia based on parent report
3. Current primary diagnosis of bipolar disorder, psychosis, substance use disorder, posttraumatic stress disorder, eating disorder, or major depressive disorder in the opinion of the PI
4. Any past or present conditions that would make treatment with buspirone unsafe
5. Current use of any of the following psychotropic medications: SSRIs, SNRIs, mirtazapine, benzodiazepines, tricyclic antidepressants, monoamine oxidase inhibitors, mood stabilizers, or antipsychotics
6. Previous adequate trial of buspirone (≥20 mg/day for at least 4 weeks) or significant adverse effects
7. Aberrant Behavior Checklist Irritability subscale score (ABC-I) ≥18
8. Pregnancy or sexual activity without the use of an acceptable form of birth control in females of childbearing age
9. Acutely unstable medical/psychiatric condition (e.g. self-injury, suicidality) that would preclude study participation in the opinion of the PI
10. Inability to tolerate Bittium Faros device in the opinion of the parent or a known allergy to adhesives
