WASHINGTON (AP) — A mind-altering medication related to the club drug Special K won U.S. approval Tuesday for patients with hard-to-treat depression, the first in a series of long-overlooked substances being reconsidered for severe forms of mental illness.

The nasal spray from Johnson & Johnson is a chemical cousin of ketamine, which has been used for decades as a powerful anesthetic to prepare patients for surgery. In the 1990s, the medication was adopted as a party drug by the underground rave culture due to its ability to produce psychedelic, out-of-body experiences. More recently, some doc...