People suffering from life-threatening cancers may benefit from taking a hallucinogenic substance called psilocybin, commonly found in magic mushrooms. Two new studies published today in the Journal of Psychopharmacology find evidence that just a single dose of the drug can produce long-lasting reductions in clinical depression, anxiety and existential worry in up to 80 percent of patients facing the prospect of potentially terminal cancer.

Roland Griffiths, who co-authored one of the studies, explained in a statement that “a life-threatening cancer diagnosis can be psychologically challenging, with anxiety and depression as very common symptoms.”

He and his colleagues recruited 51 patients with life-threatening cancers, all of whom had been diagnosed with depression or anxiety as a direct result of their condition. After receiving a dose of psilocybin, however, participants began to experience clinically verifiable improvements in their mood.

Amazingly, six months later, 78 percent of those that had been diagnosed with depression and 83 percent of those suffering from anxiety continued to benefit from reduced symptoms, with roughly 60 percent showing signs of complete remission.

For the second study, researchers gave 21 cancer patients either a dose of psilocybin or a placebo, before switching the treatments seven weeks later, so that those who originally received the placebo now got psilocybin.

Both groups began to show improvements in mood immediately after taking the hallucinogen, but not when they were given the placebo. At the six-and-a-half-month stage, these anti-depressant effects were still noticeable in approximately 80 percent of participants.

^{Depression and anxiety are understandably common among people with life-threatening cancers. prudkov/Shutterstock}

These two studies build on earlier research conducted by the Beckley/Imperial Psychedelic Research Programme, in which 67 percent of participants with treatment-resistant depression experienced an improvement in symptoms one week after taking psilocybin, with 42% in remission at three months. Amanda Feilding, co-director of the programme, told IFLScience that "participants described their experiences as transformative, enabling them to gain a new perspective on things that improved their state of mind and well-being."

While the neurological mechanisms behind this phenomenon are not yet fully understood, previous studies have shown that psilocybin –  as well as other psychedelic substances like DMT – activates the brain’s serotonin receptors. Because serotonin is one of the key neurotransmitters involved in controlling mood, scientists suspect that this may explain the anti-depressant effects of psilocybin.

Recent brain-imaging studies investigating the effects of psilocybin and LSD also showed that these substance reduce activity in the Default Mode Network, which, when overactive, can produce rigid patterns of thought and contribute to conditions like depression.

“Our results represent the strongest evidence to date of a clinical benefit from psilocybin therapy, with the potential to transform care for patients with cancer-related psychological distress,” explained study co-author Stephen Ross. "And if it's true for cancer care, then it could apply to other stressful medical conditions,” adds his colleague Anthony Bossis.