Scientists at the Johns Hopkins University School of Medicine claim to have determined the proper dose levels needed to create positive changes in attitudes, mood, life satisfaction, and behavior that persist for more than a year with the psychoactive substance in so-called "magic mushrooms."

The findings are the latest in a series of experiments done at Johns Hopkins to investigate psilocybin, a psychedelic substance contained in certain mushrooms. The findings were published online this week in the peer-reviewed journal Psychopharmacology.

“In cultures before ours, the spiritual guide or healer had to discern how much of what type of mushroom to use for what purposes, because the strength of psychoactive mushrooms varies from species to species and even from specimen to specimen," said Roland Griffiths, Ph.D., a professor of psychiatry and behavioral sciences and neuroscience at the Johns Hopkins University School of Medicine and the study's lead scientist.

"In our laboratory, weʼre working with the pure chemical psilocybin, which we can measure out precisely," he added. "We wanted to take a methodical look at how its effects change with dosage. We seem to have found levels of the substance and particular conditions for its use that give a high probability of a profound and beneficial experience, a low enough probability of psychological struggle, and very little risk of any actual harm."

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The researchers said 94 percent of the study's 18 participants rated their experiences with psilocybin as among the top five most or as the top most spiritually significant experience of his or her life at a 14-month follow-up. Eighty-four percent also reported positive changes in their behaviors, changes like improved relationships with family and others, increased physical and psychological self-care, and increased devotion to spiritual practice, which were corroborated by family members and others.

"I feel that I relate better in my marriage," one participant reported. "There is more empathy – a greater understanding of people and understanding their difficulties and less judgment."

The participants, ages 29 to 62, were screened to include only those who were deemed psychologically and physically healthy. Each participant received five closely-monitored, eight-hour psilocybin sessions a month apart. Each session had a different dose of psilocybin, with one session using a placebo, and was "blind," meaning neither the participants, the monitors, nor the scientists knew how much psilocybin - if any - had been given during any session.

At higher doses of psilocybin, nearly a third of the participants experienced great fear or had delusions, but with gentle guidance from researchers, those reactions did not outlast the psilocybin session or harm the participants. Those who received lower doses of the psychedelic before the higher doses were the most likely to have long-lasting positive changes in attitudes and behavior.

Potential psychotherapeutic value of 'magic mushrooms'

"The Hopkins psilocybin studies clearly demonstrate that this route to the mystical is not to be walked alone," Jerome Jaffe, M.D., who served as the first White House "Drug Czar," commented. "But they have also demonstrated significant and lasting benefits."

"That raises two questions: Could psilocybin-occasioned experiences prove therapeutically useful, for example in dealing with the psychological distress experienced by some terminal patients? And should properly-informed citizens, not in distress, be allowed to receive psilocybin for its possible spiritual benefits, as we now allow them to pursue other possibly risky activities such as cosmetic surgery and mountain-climbing?"

A similar study published in the Archives of General Psychiatry in January found psilocybin can safely improve the moods of patients with advanced-stage cancer and anxiety.

The study was headed by Dr. Charles S. Grob, a professor of psychiatry at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center and found a significant improvement of mood and a reduction in symptoms of anxiety up to six months after receiving psilocybin-assisted therapy.

"We are working with a patient population that often does not respond well to conventional treatments," said Grob. "Following their treatments with psilocybin, the patients and their families reported benefit from the use of this hallucinogen in reducing their anxiety. This study shows psilocybin can be administered safely, and that further investigation of hallucinogens should be pursued to determine their potential benefits."

Although some may be concerned that a relatively unstudied and illegal substance such as psilocybin could pose health risks, a study published in the Psychopharmacology in 2004 found there is "no cause for concern that [psilocybin] is hazardous with respect to somatic health" in healthy adults.

The only physiological side-effects the study found was a brief increase in blood pressure and a small increase in levels of thyroid-stimulating-hormone (TSH), prolactin, cortisol, and adrenocorticotropic hormone. None of these side-effects were considered dangerous to healthy adults.

"Typically, the experiences after [medium and high doses of psilocybin] were rated positive, with retrospective statements ranging from ‘pleasurable’ to ‘ineffably beautiful,’ " according to the study. One volunteer had a fearful experience after being given a high dose of psilocybin, but his anxiety was resolved without the need for pharmacological intervention.

"We know that psilocybin is remarkably non-toxic to the bodyʼs organ systems," Matthew Johnson, Ph.D., an assistant professor of psychiatry and behavioral sciences at Johns Hopkins and lead author of an earlier Hopkins paper on hallucinogen safety remarked. "But there are indirect risks: if someone experiences high anxiety, fear, or paranoia during a psilocybin session, itʼs not hard to imagine them behaving in ways harmful to themselves or others."

"These risks appear to be minimized when volunteers develop a trusting relationship with a skilled monitor, who remains present with them for the duration of the substanceʼs primary effects, and who is available afterwards for consultation."