In a recent study of 51 cancer patients struggling with anxiety and depression, the majority experienced relief after taking a moderately high dose of psilocybin, a substance found in certain mushrooms that causes hallucinations.

Patients were given a high dose of psilocybin in a structured, therapeutic environment. (In a different session, they were also given a lower dose.) They had session monitors to comfort them if the experience became too intense.

"On the outside, it just looks like they're lying on this white couch with eye shades and headphones on," said Dr. Matthew W. Johnson, an associate professor at Johns Hopkins University School of Medicine and one of the study's authors. "But then this person might describe this experience as one of the most or, maybe the most, powerful and meaningful experiences of their life."

Patients by and large reported a decrease in depression and anxiety around the thought of death. A six-month follow-up to the study found that decrease remained fairly constant. Johnson noted that patients with a history of psychosis should not take psilocybin.

Psilocybin is a Schedule 1 drug, which means that right now, it's seen as having no medical merit in the eyes of the law and a high risk for abuse.

But Dr. Michael Thase, a professor of psychiatry at the Perelman School of Medicine at the University of Pennsylvania, said that if psilocybin has more successful clinical trials, and then receives FDA approval — a process that would take more than five years — he could imagine clinicians prescribing the drug in the future.

"I think that the issue of stigma would be balanced by the horrors of unremitting depression," he said.

Researchers are interested in the benefits of several nontraditional drugs for treating depression because some patients don't improve when taking typical antidepressants, Thase said. Many of those alternatives are medications being tried for a secondary use.