The way it works is when people normally drink alcohol, endorphins are released into the brain, and this reinforces the behavior of drinking alcohol. Revia and Vivitrol block the feel-good endorphins. Much like when Pavlov's dogs were presented with food when a bell was rung, these dogs became conditioned to salivate at the sound of the bell alone. However, when these dogs continued to be presented with the ringing bell and no food, the salivating stopped.
Drug addiction is a chronic brain disease that causes powerful physical and psychological cravings for mind-altering substances, including illegal intoxicants like cocaine, heroin, methamphetamine, and PCP. Many people also become addicted to misused prescription drugs, or to chemical substances not manufactured for human consumption (inhalants), to party drugs (ecstasy), hallucinogens like LSD, or to marijuana, which despite its benign reputation is the most widely abused illicit drug.
Stimulants, such as tobacco, cocaine or prescription amphetamines, stimulate the brain and nervous system, causing increased alertness. Depressants, such as barbiturates and benzodiazepines, slow activity in the brain and nervous system, causing relaxation. Hallucinogens, such as LSD and PCP, drastically disrupt the way the brain and nervous system communicate, causing hallucinations. Rehab: Last Week Tonight with John Oliver (HBO)