Investigating the efficacy of a form of TMS called theta-burst stimulation for restricted and repetitive behavior in ASD.

Inclusion criteria.

1. Diagnosis of Autism Spectrum Disorder (ASD)
2. Meet criteria for Autism Spectrum Disorder (ASD) on clinical assessments (ADOS-2 or CARS if conducted remotely & ADI-R)
3. Aged between 12-45 years old
4. Have a reliable informant who can complete relevant questionnaires
5. Have DARB scores which indicate high levels (50% or above) of RRB on one of the following domains: Insistence on Sameness, Obsessive Compulsive Behaviors, and Unusual Interests

Exclusion criteria.

1. Any contraindications for TMS e.g. history of seizures other than clear substance-induced/fever-induced seizures with neurologist note or normal clean EEG and no seizure in at least 12 months prior to enrollment.
2. Pregnancy.
3. Any current or past history of any physical condition which in the investigator's opinion might put the subject at risk or interfere with study results interpretation.
4. Active substance use (<1 week) or intoxication verified by toxicology screen--of cocaine, amphetamines, benzodiazepines.
5. Showing symptoms of withdrawal from alcohol or benzodiazepines.
6. DSM-5 diagnosis of bipolar disorder or a psychotic disorder e.g. schizophrenia.
7. Significant sensory impairments such as blindness or deafness.
8. Current severe insomnia (must sleep a minimum of 4 hours the night before stimulation).
9. Not willing to cooperate with the TMS procedures.
10. Currently taking Clozapine or another medication that the PI determines increases the risk of TMS or may disrupt the efficacy.
11. A motor threshold that is too high to allow safe/tolerable treatment.
12. Conditions that increase the risk for COVID-19 (in accordance with university guidelines).