Psilocybin for Anorexia Shows Promise in Early Trial

Just a single dose of psilocybin was safe and tolerable for adult women with anorexia, according to a phase I open-label feasibility study.

After receiving a 25-mg dose of synthetic psilocybin given with therapist-delivered psychological support, none of the 10 participants experienced any significant changes in vital signs, ECGs, or suicidality during the week after dosing, reported Stephanie Knatz Peck, PhD, of the University of California San Diego, and colleagues.

Meeting the primary outcome, the treatment was also well-tolerated, with no serious adverse events reported amongst participants, who had an average body mass index (BMI) of 19.7, they noted in Nature Medicine.

The most common adverse events were headache (80%), fatigue (70%), and nausea (30%), but these were generally transient. Two participants developed asymptomatic hypoglycemia, both of whom were required to eat breakfast at the clinic prior to receiving psilocybin, leading to resolution within 24 hours.

As for changes in psychopathology — the secondary outcome of the early-stage trial — concerns about weight significantly decreased from baseline to 1 month after psilocybin treatment. This improvement was also maintained up to 3 months after dosing. Likewise, shape concerns significantly dropped within the month after treatment, but this change was no longer significant at the 3-month mark.

Changes in eating concerns and dietary restraint didn’t reach statistical significance, but there was a trend towards an improvement in eating concerns at the 3-month follow-up.

“Effects of treatment were, however, highly variable among participants,” Knatz Peck’s group pointed out.

While there wasn’t a significant change in BMI seen across the entire cohort, a few participants did see an increase in BMI during the 3-month follow-up, ranging from 0.4 to 1.2 kg/m².

While psychopathology efficacy was variable, the vast majority of participants had positive perceptions of the treatment experience. Ninety percent said they felt more optimistic regarding their life endeavors 3 months after the psilocybin dosing, and 80% said the psilocybin dosing was one of the top-five most meaningful experiences of their life. Likewise, 70% said the overall quality of their life improved and that they felt a shift in their personal identity or a sense of who they are, while 60% said they felt a greater sense of spirituality and that the importance they place on their physical appearance decreased.

Interestingly, nine of the 10 participants said that they felt one dosing session was not enough.

All participants met the DSM-5 criteria for anorexia nervosa (AN) or partial remission of anorexia, but most disorders were mild to moderate in severity. “Despite its seriousness, there are no proven treatments for adult AN that reverse core symptoms and no approved pharmacological interventions,” the researchers pointed out.

“Novel and innovative treatment methods are urgently needed to improve treatment engagement and outcomes,” they added. “One such avenue may be psilocybin therapy.”

This study comes alongside a recent push towards testing psilocybin — contained in the psychoactive drug “magic mushrooms” — for a slew of various psychiatric conditions.

Study sponsor Compass Pathways, who provided the investigational drug COMP360 — a proprietary pharmaceutical-grade synthetic psilocybin formulation — has also successfully tested this compound in people with treatment-resistant depression, which worked just as well with or without antidepressants or antipsychotics. COMP360 is also currently in late-stage testing for post-traumatic stress disorder.

This early-stage study was limited in its small sample size and lack of a control comparison group.

In July 2022, Compass Pathways announced the launch of a phase II trial that will test psilocybin at 25-mg and 1-mg doses in 60 participants with either the restrictive or binge-purge subtypes of anorexia.

“[F]uture studies are needed for optimization to identify adequate dosage, identify the optimal number of psilocybin administrations and investigate the need for possible adjunctive treatments that could optimize treatment outcomes,” Knatz Peck and colleagues concluded.