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Psilocybin Is Safe to Give to Anorexic Patients, Trial Finds

A magic mushroom in a test tube.
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Psilocybin is a safe and tolerable drug to give to anorexia patients, according to a new study.

Researchers gave the ‘magic mushroom’ drug to ten participants with anorexia, who then received follow-up psychological support.

None of the participants experienced any serious adverse effects from the drug. On average, the participants reported a significant decline in concerns about their physical shape, one month after taking psilocybin. This psychological benefit, however, was reduced at the three-month follow-up assessment.

Regardless, four patients did demonstrate decreases in eating disorder scores at the three-month follow-up, which qualified them for remission from eating disorder psychopathology.

The study was published in Nature Medicine.

Shrooms for anorexia

Anorexia nervosa is a mental health disorder characterized by severe restriction of calorie intake and a preoccupation with weight and shape.

Given that the condition is considered “ego-centric”, and psilocybin is known to alter ego-consciousness, the researchers behind the new study wondered whether the magic mushroom drug could have a place in anorexia management.

To test this idea, the researchers from the University of California, San Diego, and the University of Michigan Medical School gave ten participants with anorexia (all female) a 25 milligram (mg) dose of COMP360, a synthetic form of psilocybin manufactured by the study’s sponsor, Compass Pathways.

The participants spent the next eight hours in a room with two psychologists while the drug’s effects played out. The participants saw the psychologists again the day after they took the drug for further assessment. Further appointments with the psychologists were scheduled a week after they took the drug, a month after and three months after.  

The researchers were primarily looking to see if the participants’ eating disorder examination scores dropped after their psilocybin sessions – and many did. The day before their psilocybin sessions, the participants had an averaged “eating concern” score of 2.1 and averaged “shape concern” score of 3.68. One month after taking psilocybin, these averages dropped to 1.24 and 2.43, respectively. However, these averages – and all the average scores – had wide standard deviations (the variability of the mean) due to the varied experiences of each participant and how few participants there were in the study.

Because of these factors, it’s difficult to definitively say that the psilocybin helped the patients manage their anorexia.

“This study does not demonstrate that psilocybin therapy can be used to treat anorexia nervosa,” Trevor Steward, a senior research fellow at the University of Melbourne – who was not involved in the study – said in a statement.

Instead, Steward and other observers of the trial say that the study’s main finding is that psilocybin is a safe and tolerable drug to give to anorexia patients. After all, no serious adverse events were reported. Two participants did develop hypoglycemia (low blood sugar levels), but these incidences were without symptoms and resolved in 24 hours without medical intervention.

“This study represents an important first step towards determining how safe and well-tolerated psilocybin therapy is for adult patients with anorexia nervosa,” Steward said.

Nonetheless, other observers have emphasized that four participants (40% of sample) in the trial did demonstrate significantly lower eating disorder examination scores at the three-month follow-up. While this result is somewhat compromised by the variability of the other average scores and the low sample size, expert observers say it shows hope that further, more comprehensive trials can uncover a true clinical benefit of psilocybin in anorexia treatment.  

“It’s important to recognize that while the effects of psilocybin therapy on eating disorder symptoms in this study were exploratory in nature and highly variable among the ten participants included, four individuals (40%) demonstrated clinically significant reductions in symptom presentation three months after the experience,” Claire Foldi, a senior research fellow at the Monash University Biomedicine Discovery Institute –who was also not involved in the study – said in a statement.

“A major limitation of this study, duly noted by the authors, was that it included a small, self-referred and therefore perhaps non-representative clinical sample,” she added. “In addition, the lack of a control comparison precludes the possibility that an expectation of positive outcomes may have influenced these findings.”

“These caveats aside, the results offer promise in the pursuit of larger, adequately controlled trials that will determine whether psilocybin-assisted psychotherapy could aid in the unmet need for effective treatment options for individuals suffering from anorexia nervosa.”

Reference: Peck SK, Shao S, Gruen T, et al. Psilocybin therapy for females with anorexia nervosa: a phase 1, open-label feasibility study. Nat Med. 2023:1-7. doi:10.1038/s41591-023-02455-9