In the 1950s, scientists on a mission to create better anesthesia drugs synthesized phencyclidine, commonly known as PCP. Though PCP worked well to keep most people unconscious during surgical procedures, some experienced what the authors of a 1959 trial described as “delirium and hallucinations which, although usually of a highly pleasurable nature, are sometimes rather terrifying to the patients.” This so-called dissociated state—when what the brain experiences is disconnected from reality—lasted as long as 12 hours.
Seeking a shorter-acting agent, researchers in the 1960s made a compound that’s structurally related to PCP called ketamine. Ketamine remains a common anesthetic today, says Joe Cichon, a neuroscientist and anesthesiologist at the University of Pennsylvania’s Perelman School of Medicine. At lower doses than would be used for anesthesia, people remain conscious yet experience a similar dissociated state as with PCP but for far less time. In the 2000s, researchers found that these lower, ...
