Recent studies showed that a single dose of psilocybin reduces anxiety and depression in cancer patients:
About 80 percent of cancer patients showed clinically significant reductions in both psychological disorders, a response sustained some seven months after the single dose. Side effects were minimal.
In both trials, the intensity of the mystical experience described by patients correlated with the degree to which their depression and anxiety decreased.
The studies, by researchers at New York University, with 29 patients, and at Johns Hopkins University, with 51, were released concurrently in The Journal of Psychopharmacology. They proceeded after arduous review by regulators and are the largest and most meticulous among a handful of trials to explore the possible therapeutic benefit of psilocybin.
One theory is that psilocybin interrupts the circuitry of self-absorbed thinking that is so pronounced in depressed people, making way for a mystical experience of selfless unity.
More from another article:
In the Johns Hopkins study, half of the 51 participants were given a low dose of psilocybin as control, followed by a high dose five weeks later. (For the other half, the order of the doses was reversed.) The results were remarkable: Six months later, 78 percent of the participants were less depressed than they started, as rated by a clinician, and 83 percent were less anxious. Furthermore, 65 percent had almost fully recovered from depression, and 57 percent from their anxiety, after six months. By comparison, in past studies antidepressants have only helped about 40 percent of cancer patients, performing about as well as a placebo. At the six-month follow-up, two-thirds of the participants rated the experience as one of the top five most meaningful of their lives. They attributed their improvements to positive changes in their attitudes about their lives and their social relationships. Their quality of life improved, as did their feelings of “life meaning” and optimism—even though several of them would later die. “People will say, ‘I know I’m dying, I’m sad that I’m dying, but it’s okay,” Griffiths said. “Things are going to be alright.”
The New York University study was very similar, but it had only 29 participants and used niacin, a vitamin, as a placebo. (Halfway through the experiment, the participants switched groups.) It also included a more formal psychotherapy component, in which the participants would discuss their trips. That study similarly found that the psilocybin had both immediate and enduring effects. Six months after the treatment, 60 to 80 percent of the participants saw improvements in various measures of depression and anxiety, and 70 percent considered it one of the top five most personally meaningful experiences of their lives.
“The most surprising thing to me is that this actually worked. I was highly skeptical,” said Ross, the lead NYU study author. Before the treatment, some of the participants would cry and shake when they talked about their cancer. But “the moment they get psilocybin, their distress comes down. That’s very new in psychiatry, to have a medication that works immediately for depression and anxiety and can last for that long.”
The researchers aren’t sure exactly how psilocybin works—a rather common problem in drugs aimed at brain chemistry. Psilocybin seems to quiet the prefrontal cortex, a part of the brain where increased activity has been associated with depression. It also might be acting on the brain’s use of glutamate, a neurotransmitter that affects learning and memory. Ross said what might be happening is a sort of “inverse PTSD”—a profoundly positive memory that affects participants for months, much like a severe trauma might in post-traumatic stress disorder.
It’s also possible that the sheer mysticism of the experience was enough to prompt a change in mood. “There’s a sacredness or a reverence to that experience … it’s also accompanied by positive mood, in the sense of an open-heartedness, love or benevolence,” Griffiths said. Participants might have a sense that “the experience is more real and more true than everyday waking consciousness. Although the effects of the drugs are gone by the end of the day, the memories of these experiences and the attributions made to them endure.” It’s not uncommon, he said, for study participants to say they think about their psilocybin experience every day.
Smaller studies have hinted at the drug’s effectiveness in treating alcoholism, obsessive-compulsive disorder, treatment-resistant depression, and smoking. It’s also been found to help change peoples’ personalities, making them more “open,” meaning imaginative or broad-minded.