Everyone’s depression is different, but Ted, a 40-year-old resident of Portland, Oregon, describes his as a “continuous dark veil — a foul, dark, awful perspective that informs every moment of your whole life.” He’d tried to treat it with antidepressants, therapy, visits to psychiatrists, “the whole nine,” but although the antidepressants kept him functional, they by no means offered relief. He was getting desperate, so when his sister — an obstetrician who works in New York — mentioned the National Institute of Health was conducting experimental studies using ketamine to treat depression, he gave them a call.

The use of ketamine to treat depression is still fairly novel. It was originally developed in 1962 as a general aesthetic; it can knock someone out without slowing down their heart rate, which comes in handy in combat situations where breathing tubes aren’t readily available. (It’s also useful for operations on children, who are sometimes too small to use a breathing tube.) It also produces a hallucinogenic effect when taken in large doses in a relatively short period of time. Illegal use of ketamine took off in the ’70s and ’80s, and the Center for Substance Abuse Research estimates it’s even more popular today, although its production and distribution is more tightly restricted.

But since 2006, multiple studies have shown that extremely low doses of ketamine can also reverse the effects of the most severe depression — depression like Ted’s that once seemed untreatable. “The response rate is unbelievable,” Dr. Enrique Abreu, who runs the Portland Ketamine Clinic, and whom Ted sees about once every three weeks, told the Washington Post. “This drug is 75 percent effective, which means that three-quarters of my patients do well. Nothing in medicine has those kinds of numbers.” To read more from Claire Landsbaum, click here.