What Is A Drug?

Almost all of the drugs that change the way the brain works do so by affecting chemical neurotransmission. Some of these drugs,
    • mimic the effect of a neurotransmitter,
    • prevent messages from getting through,
    • interfere with the molecules responsible for transporting neurotransmitters back into the neurons that released them,
    • or, cause neurotransmitters to be released in greater amounts than normal.
Drugs that affect the feelings, perceptions, or behavior of the user have psychoactive (mind-altering) properties.