Accelerated and Extended-iTBS Targeting Inhibitory Control in Veterans With ADHD

Inclusion Criteria: * Diagnosis of ADHD predominantly hyperactive-impulsive or combined, as outlined in the DSM-5-TR criteria * Maintenance of clinical symptoms despite receiving stable treatment for a minimum of 6 weeks before the study procedures * Capability to comprehend and provide informed consent * For safety reasons, participants must meet established screening criteria to ensure safety during Magnetic Resonance Imaging (MRI) scans * This precaution is taken due to the novel application of iTBS in this specific population, as MRI involves exposure to magnetic fields similar in intensity to those emitted from the stimulation coil * As such, participants must not have the following, unless the devices are MRI-safe: * cardiac pacemaker * implanted devices (such as deep brain stimulators) * metal in the brain * cervical spinal cord, or upper thoracic spinal cord level * In addition, eligible Veterans must also be able and willing to comply with all study procedures and visits * Throughout the study, pharmacologic and psychotherapeutic regimens will tentatively remain unchanged Exclusion Criteria: * Primary psychotic disorders, bipolar I disorder, ongoing severe substance use disorders, or active suicidality * Non-MRI safe cardiac pacemakers, implanted devices, or metallic implants at the upper thoracic spine level or higher * Any of the Transcranial Magnetic Stimulation (TMS) specific exclusion criteria, including: * pregnancy * lactation * planning pregnancy during period of study * history of moderate or severe traumatic brain injury * active unstable medical conditions * CNS tumors * seizures * cerebrovascular disease * other severe neurological disorders * Additional exclusion criteria include the presence of any other condition or circumstance that, as determined by the investigator team, has the potential to prevent study completion or introduce confounding effects in outcome assessments