The positive psychological effects of psilocybin – the active ingredient in hallucinogenic mushrooms – last for more than a year, say scientists.

Fourteen months after taking psilocybin pills administered by Johns Hopkins neuroscientist Roland Griffiths, more than half of 36 volunteers said the experience was among the most significant of their lives.

The results, published today in the Journal of Psychopharmacology, demonstrate the persistence of effects first reported by Griffiths in a landmark 2006 experiment. That study, published in Psychopharmacology, was the first in 40 years to test a hallucinogen on people in a clinical setting in the United States.

Formerly the focus of academic and government inquiry, hallucinogens were abandoned by researchers in the aftermath of the Sixties, when rampant recreational abuse frightened authorities and the drugs became culturally intertwined with chemical excess. But with a small but growing number of researchers now studying hallucinogens, the once-promising field is alive again.

"These drugs are no longer being confined to rats in test tubes," said David Nichols, a Purdue University pharmacologist who was not involved in the study. "What we're looking at is a largely unexplored technology for brain science – it was discovered in the 1940s, set the psychiatry world ablaze in the 1950s, and was aborted by widespread recreational abuse, the reaction of the media and its confluence with the Vietnam war."

For the 2006 study, Griffiths recruited 36 people who hadn't previously taken the drug. Six were given a ritalin placebo, while the rest received 30 milligrams of pure psilocybin – a dose roughly equivalent to five grams of dried psilocybe cubensis mushrooms, though mushroom potency varies widely. Psilocybin works by activating serotonin receptors in the brain, though the precise neurological cascades have not yet been identified.

Volunteers took the dose under the guidance of two trained mentors, with the traditional laboratory setting scrapped in favor of a living room appointed with a comfortable couch, headphones and other spiritual journey aids.

At the time, the volunteers reported mystical experiences – typically described as a "sense of unity" – in which the confusion of the world and of competing value systems came together in a coherent whole. These were not described in recreational terms, but as profoundly meaningful spiritual events. Fourteen months later, over half reported substantial increases in life satisfaction and positive behavior, while no long-term negative effects were reported.

"These appear to be life-altering experiences that have much in common with classical mystical experiences described throughout the ages,"

Griffiths said. "The persistence and salience of the effects didn't diminish by 14 months, and that is noteworthy. It's one thing to have a meaningful experience, but 14 months later, you might be hard-pressed to remember it. But in this case, you have an eight-hour session in a lab, and 14 months later you have 60 percent of them saying it's among the five most personally meaningful experiences of their lives."

Griffiths noted that psilocybin isn't for everyone: though physiologically non-toxic and non-addictive, users may experience short-term stress and panic – i.e., bad trips – or trigger pre-existing psychoses. Prospective volunteers with personal or family histories of psychotic disorders were disqualified from the experiment.

An accompanying Journal of Psychopharmacology article, co-authored by

Griffiths and Johns Hopkins psychiatrist Matt Johnson, gives guidelines for testing hallucinogens in a clinical setting: screening volunteers, preparing them, training monitors, conducting the session and providing support afterward.

"It's a blueprint for a clinical researcher interested in undertaking a trial like this," said Griffiths. "In some ways it may be a more important paper."

Such guidelines, said Griffiths, are needed to taking hallucinogen research out of the wilderness in which it's resided since the 1960's, when research was abandoned.

"As a culture, we experienced such trauma because of what happened in the 1960's – not just here, but worldwide. All major clinical research with classical hallucinogens was eliminated, and that was largely the case for 40 years," said Griffiths. "It's really quite unprecedented to have a situation in which a unique and very interesting compound is simply not studied for a long period of time."

Griffiths said that his lab has now run more than 100 psilocybin sessions, and since his 2006 paper several other U.S. laboratories have received approval for their own hallucinogen trials.

"I think we're seeing a sea change, and it's now become acceptable to conduct these trials under very careful conditions," said Griffiths.

"It's very exciting from a scientific point of view. There's so many things that can be addressed: investigating the consequences of these kinds of experiences from a neurophysiological perspective, where in the brain and how in the brain it happens. More broadly, the consequences of these experiences – how they unfold and manifest in people's lives. And, finally, the therapeutic targets."

Nichols said that hallucinogens may be useful in treating pain and anxiety as well as eating disorders and obsessive-compulsive disorder, the latter of which are poorly handled by current pharmaceuticals.

Griffiths is studying the therapeutic application of psilocybin to people distressed by cancer diagnoses. He also hopes to study the possibilities of psilocybin in reducing drug and alcohol dependence.

"Those are the main therapeutic targets," he said. "But what the mystical experience means, how it can be harnessed and where we can go from here – that's wide-open for science to explore."

Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later [Journal of Psychopharmacology]

Human hallucinogen research: guidelines for safety [Journal of Psychopharmacology]

Image: Kevin Hutchinson

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