Adderall 20mg is primarily prescribed for: Attention Deficit Hyperactivity Disorder (ADHD): Helps improve focus, attention, and control of impulsive behavior. Narcolepsy: Helps manage excessive daytime sleepiness.Adderall is a central nervous system stimulant. It increases levels of certain neurotransmitters in the brain (dopamine and norepinephrine), which helps improve attention and reduce hyperactive and impulsive behavior.