definition of Adderall (amphetamine): Adderall XR® is the slow release form. Adderall® is a central nervous system stimulant that affects chemicals in the brain and in nerves. These brain chemicals (neurotransmitters) regulate activity and impulse control. Adderall is prescribed for attention deficit hyperactivity disorder (ADHD) and narcolepsy (falling asleep). It may also be prescribed off-label for people with autism. Caution: amphetamines have a high potential for abuse. Administration of amphetamines for long periods may lead to drug dependence and must be avoided. Particular attention should be paid to the possibility of subjects obtaining amphetamines for non-therapeutic use or distribution to others, and the drugs should be prescribed or dispensed sparingly. Misuse of amphetamine may cause sudden death and serious cardiovascular adverse events.