Alcohol and illicit drugs are all psychoactive drugs. Psychoactive drugs are drugs that affect the Central Nervous System, altering its regular activity. They cause changes in a person’s mood, behavior, and awareness. Psychoactive drugs are usually broken down into four categories: depressants, stimulants, opioids, and hallucinogens. They also include antidepressants, anxiety-relieving medicines, and other psychiatric medications.