This is a 6-month trial in adults to find out if certain neuromarkers can predict individual treatment response to stimulant medications for Attention Deficit Hyperactivity Disorder (ADHD). Males and females, ages 18-45, will complete an MRI scan at MIT prior to beginning medication for ADHD as determined by a treating clinician outside the context of this study.

Inclusion Criteria:

• Male and female adults ages 18-55
• A diagnosis of DSM-V ADHD based on clinical assessment supported by the ADHD module of a structured diagnostic interview
• Proficiency in English
• Right-handed

Exclusion Criteria:

• Any contraindication for the use of a stimulant medication
• Investigator and his/her immediate family (spouse, parent, child, grandparent, or grandchild)
• Any contraindications for MRI examination (metallic implants, such as pacemakers, surgical aneurysm clips, or known metal fragments in the body)
• Women who are currently pregnant or breastfeeding, as confirmed by a urine pregnancy test
• Clinically significant abnormal baseline laboratory values, including systolic and diastolic blood pressure parameters above 140 and 90, respectively and resting heart rate outside 60-100 bpm