Inclusion Criteria:
* Be currently enrolled either full time or part time as an undergraduate in a 2-year or 4-year college
* Be between the ages of 18-29
* Be a native English speaker
* ADHD Participants: Must report a prior diagnosis of ADHD and self-report five or more inattention (IA) symptoms on the DSM-5 Symptom Checklist on the pre-screener.
* Healthy Participants: Must disavow ever being diagnosed with ADHD, report 3 or fewer IA symptoms and 3 or fewer hyperactivity/impulsivity (HI) symptoms on the DSM-5 ADHD Symptom Checklist in the pre-screener and are an age and sex match of an ADHD group participant
Exclusion Criteria:
* Not meeting any of the above stated inclusion criteria
* Any contraindications for physical exercise placing the participant at moderate or high-risk. This includes the following:
1. Participants will be excluded if they report having an acute or uncontrolled disease (cardiovascular, pulmonary, neurological, endocrine, musculoskeletal, immunological).
2. Participants will be excluded if they are non-ambulatory or rely on walking aids for ambulation.
3. Participants will be excluded who chronically manage asthma or another respiratory condition or require using an inhaler to complete exercise.
4. Participants will be excluded if they experience uncontrolled or current problems with syncope (loss of consciousness or fainting) or postural hypotension.
5. Participants will be excluded if they have ever had a stroke, aneurysm, or transient ischemic attack (TIA).
6. Participants will be excluded if they have exercise or physical activity restrictions imposed by a health provider.
7. Participants will be excluded by the medical director due to possible underlying disease/condition or risk.
8. Participants will be excluded if they are pregnant (determined by a urine pregnancy test), are attempting to become pregnant, or are currently breastfeeding will also be excluded (stated above).
9. Participants will be excluded for any current use of other psychotropic drugs (e.g., SSRIs, SNRIs, sedatives; stated above).
* Any contraindications for stimulant medication use placing the participant at moderate or high-risk. This includes the following:
1. Participants will be excluded if they have ever been diagnosed with seizure disorder, high blood pressure, glaucoma, gastrointestinal hypermotility disorder (e.g., IBS), diabetes, hypoglycemia, cardiac problems (e.g., heart disease), or thyroid problems.
2. Participants will be excluded if they have ever been diagnosed with a bipolar disorder (e.g., Bipolar I or Bipolar II), a psychotic disorder (e.g., schizophrenia), a sleep disorder (e.g., narcolepsy), an eating disorder (e.g., bulimia nervosa), or a severe substance use disorder (e.g., endorsing six or more symptoms of a substance use disorder according to the DSM-5). Participants will also be excluded if they report a past year diagnosis of major depressive disorder, panic disorder, generalized anxiety disorder, or any substance use disorder.
3. Participants will be excluded if they report any prior treatment for substance use (e.g. rehabilitation for alcohol or other substance use). Additionally, participants will be excluded if they do not agree to abstain from illicit or addictive drugs and marijuana use for the duration of the study beginning with the eligibility assessment.
4. Participants will be excluded if they experience uncontrolled or current problems with syncope (e.g., loss of consciousness or fainting) or postural hypotension.
5. Participants will be excluded if they are pregnant (determined by a urine pregnancy test), are attempting to become pregnant, or are currently breastfeeding.
6. Non-ADHD participants will be excluded if they have ever engaged in non-prescription stimulant use.
7. ADHD participants who are currently prescribed a prescription stimulant will be asked not to take their medication the day prior to and day of any study visits. They will be excluded if they are not comfortable with abstaining.
8. Participants will be excluded for any current use of other psychotropic drugs (e.g., SSRIs, SNRIs, sedatives) or non-stimulant ADHD medication (i.e., Strattera).
9. Participants will be excluded for any current use of any other prescription medication that could interact negatively with Adderall (e.g., neurological and blood-pressure drugs, antihistamines).
10. They will also be excluded for current use of high levels of caffeine consumption (e.g., daily use more than 600mg/day or about six 8-oz. cups of coffee). Daily use is defined as 5 or more days per week for the last month.
11. Participants who are using other over-the-counter-substances that could interact negatively with Adderall (e.g., dietary supplements, weight-loss pills, and low-to-moderate levels of caffeine consumption, antihistamines) will be asked to abstain from use for at least 12-hours prior to lab visits. They will be excluded if they are not comfortable with abstaining.
12. Participants will be excluded if they report current nicotine use (i.e., 5 or more cigarettes per day), daily vaping (i.e., e-cigarettes), smokeless tobacco (i.e., chewing tobacco), nicotine gum, and/or nicotine patches use in the past month.
13. Participants will be excluded if they experienced a concussion within the past 6 months, have experienced two or more concussions in their lifetime, or have a history of traumatic brain injury.
14. Participants will be excluded if they have ever had a stroke, aneurysm, or transient ischemic attack (TIA).
15. Participants will be excluded if they are unwilling to ingest a prescription stimulant medication (Adderall) or placebo in the lab.
