Inclusion Criteria:
1. Ability to provide assent and have parent provide parental permission
2. English fluency of the participant and the legal guardian/parent
3. 12-18 years
4. Parent rating on BRIEF-2 Working Memory: Greater than 1.0 SD above normative mean.
5. IQ \> 80
6. Clinical diagnosis of attention deficit hyperactivity disorder (ADHD): predominantly inattentive type, predominantly hyperactive/impulsive type, combined type, or unspecified type. Diagnostic criteria will be confirmed with NICHQ Vanderbilt Assessment Scales-Parent.
7. Participants are allowed to continue clinical ADHD treatments. However, changes to ADHD treatments cannot be made during the entirety of study participation. Confirming a plan of treatment stability will occur as part of initial inclusion criteria. We will check on treatment stability at the start of each two-week phase with the participant and parent, and document accordingly. Changes to treatment will be reviewed by a physician and may result in study termination.
Exclusion Criteria:
Participants will be screened to exclude individuals with neurological or medical conditions that might confound the results, as well as to exclude participants in whom MRI or TMS might result in increased risk of side effects or complications. Common contraindications include metallic hardware in the body, cardiac pacemaker, patients with an implanted medication pumps or an intracardiac line, or prescription of medications known to lower seizure threshold. These account for the majority of the exclusion criteria listed below:
1. Intracranial pathology from a known genetic disorder (e.g., NF1, tuberous sclerosis) or from acquired neurologic disease (e.g. stroke, tumor), cerebral palsy, history of severe head injury, or significant dysmorphology
2. History of fainting spells of unknown or undetermined etiology that might constitute seizures
3. History of seizures, diagnosis of epilepsy, or immediate (1st degree relative) family history epilepsy
4. Any progressive (e.g., neurodegenerative) neurological disorder
5. Chronic (particularly) uncontrolled medical conditions that may cause a medical emergency in case of a provoked seizure (cardiac malformation, cardiac dysrhythmia, asthma, etc.)
6. Contraindicated metal implants in the head, brain or spinal cord (excluding dental implants, braces or fillings)
7. Non-removable makeup or piercings
8. Pacemaker
9. Implanted medication pump
10. Vagal nerve stimulator
11. Deep brain stimulator
12. TENS unit (unless removed completely for the study)
13. Ventriculo-peritoneal shunt
14. Signs of increased intracranial pressure
15. Intracranial lesion (including incidental finding on MRI)
16. History of head injury resulting in prolonged loss of consciousness
17. Substance abuse or dependence within past six months (i.e., DSM-5 substance use disorder criteria)
18. Chronic treatment with prescription medications that decrease cortical seizure threshold, not including psychostimulant medication if deemed to be medically safe as part of the medical review process.
19. Active psychosis or mania
20. Current suicidal intent
21. Current pregnancy
22. Significant visual, hearing or speech impairment
23. Current wards of the state
