Inclusion criteria for autistic adults:
- Autistic adults (≥18 years old), confirmed by Autism Diagnostic Observation Schedule.
- DSM-5 severity level of ASD: level 1 or level 2
Inclusion criteria for typically developing control:
- ≥18 years old without autism spectrum disorder
Exclusion criteria for all participants:
- Previous or current severe neurological disorders, especially epilepsy
- Previous or current severe systemic diseases such as cardiovascular disease, diabetes or hypertension
- Previous or current severe brain injury
- Implementation of metal materials such as a pacemaker or medication pump
- Previous or current severe psychiatric disorders such as schizophrenia, bipolar disorder, severe major depressive disorder or substance abuse
- Pregnancy
- Intracranial space occupied lesions
- Previous brain surgery or central nerve system infection
- Concurrent use of medications which increased the risk of seizure attack
- Participate in another clinical trial within one month
- With damaged skin at the stimulated region
- With multiple sclerosis
- With large ischemic scars
- Have experienced sleep disorders during brain stimulation
- Severe alcoholism
- Concurrent use of antiepileptic drugs
- Uncontrollable migraines due to increased intracranial pressure
- Unsuitable for MRI (e.g. those with claustrophobia)
- Unsuitable for EEG
- DSM-5 severity level of ASD: level 3
- Suicidal ideation within one year
Withdrawal criteria:
- Seizure attack during the study period
- Autistic symptoms worsened obviously during the study period (change of DSM-5 severity level)
- Extreme agitation or irritability during the study period
- Participants request
- Clinical symptoms worsened obviously during study period
- Start to use antiepileptic drugs during study period
- Suicidal ideation or self-harm behaviors during study period