Adderall 20mg is primarily prescribed to treat attention deficit hyperactivity disorder (ADHD) and narcolepsy. It contains a combination of amphetamine and dextroamphetamine, which are central nervous system stimulants. In ADHD, it helps improve focus, attention span, and impulse control by increasing the levels of certain neurotransmitters in the brain. For narcolepsy, it aids in controlling excessive daytime sleepiness and sudden attacks of sleep. However, it’s important to use Adderall under medical supervision due to its potential for abuse and dependence.