A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain.Depressants are also occasionally referred to as downers as they lower the level of arousal when taken.istilled (concentrated) alcoholic beverages, often called  hard liquor , roughly eight times more alcoholic than beer. An alcoholic beverage is a drink that contains ethanol, an anesthetic that has been used as a psychoactive drug for several millennia. Ethanol is the oldest recreational drug still used by humans.