Since childhood, Rachael Petersen had lived with an unexplainable sense of grief that no drug or talk therapy could entirely ease. So in 2017 she volunteered for a small clinical trial at Johns Hopkins University that was testing psilocybin, the active ingredient in magic mushrooms, for chronic depression.
“I was so depressed,” Ms. Petersen, 29, said recently. “I felt that the world had abandoned me, that I’d lost the right to exist on this planet. Really, it was like my thoughts were so stuck, I felt isolated.”