In brief
- A team from the University of California, San Diego, tested a single 25 mg dose of psilocybin, paired with psychological support, in ten women with anorexia nervosa for the first time.
- The objective was safety and feasibility, not efficacy: there were no serious adverse effects, and the majority described the session as a meaningful experience.
- Changes in symptoms were variable, and the study is too small to speak of a treatment; it is a first step, not proof that it works.
Anorexia nervosa is one of the mental disorders with the highest mortality rates and the most resistance to available treatments. In that context, a U.S. research team asked a question that must precede all others: is it even safe and feasible to administer psilocybin to people with this diagnosis? The result, published in Nature Medicine in 2023, is the first feasibility study on this combination, and it should be read for what it is: a cautious starting point, not an announcement of a cure.
The study
The work, authored by Stephanie Knatz Peck, Walter H. Kaye, and colleagues at the University of California, San Diego, was a phase 1, open-label trial without a control group. Ten adult women (average age of 28) who met the DSM-5 diagnostic criteria for anorexia nervosa participated. Each received a single 25 mg dose of synthetic psilocybin (the COMP360 formulation) accompanied by psychological support before, during, and after the session. The design is important: because it was open-label, both the participants and the team knew what was being administered, and since there was no placebo or comparison with another treatment, it is impossible to attribute any changes to the molecule with certainty. The stated objective was not to demonstrate efficacy, but to evaluate safety, tolerability, and acceptability: to record adverse effects, electrocardiogram alterations, laboratory tests, vital signs, and any signs of suicidal ideation.
What was found
Regarding safety, which was the central question, the results were reassuring within the controlled clinical framework in which they were conducted. There were no serious adverse effects. All those described were mild and transient: headache (in 80% of participants), fatigue (70%), and nausea (30%). No clinically relevant changes were observed in electrocardiograms, vital signs, or suicidal ideation. Two participants experienced asymptomatic hypoglycemia after treatment that resolved in less than 24 hours, a relevant detail precisely because of the nutritional status inherent to this disorder.
As for the symptoms of the disorder, the figures should be viewed with caution. At the one-month follow-up, statistically significant decreases were observed in concerns about weight and body shape (both with p = 0.036 and a moderate-to-high effect size), as well as improvements in trait anxiety and body image. However, body weight (body mass index) showed no significant changes and varied greatly from one person to another. After three months, four of the ten participants had eating symptom scores within the range of the general population. The authors themselves warn that they did not correct the analyses for multiple comparisons, which requires these values to be read as exploratory.
Perhaps the most striking finding was in the subjective assessment. 80% ranked the session among the five most meaningful experiences of their lives, 90% said they felt more positive about their future, and 70% reported an improvement in their quality of life and a change in their relationship with their own identity. At the same time, 90% considered that a single session was insufficient.
What it means (and what it doesn’t)
This study demonstrates one concrete and valuable thing: in a clinical setting, with participant selection and psychological support, administering a dose of psilocybin to people with anorexia nervosa was feasible and did not produce serious short-term harm. That is not insignificant in a disorder where many treatments fail or where people drop out of therapy. But it does not follow that psilocybin is an effective treatment for anorexia, and the researchers themselves are the first to emphasize this: they speak of “preliminary and inconclusive” results due to the size and design of the study.
The limitations are numerous and honest. Only ten people, all women, with little cultural and racial diversity, and mostly with mild or moderate forms of the disorder. There was no comparison group, so the placebo effect, human support, and expectation—fueled by the enormous media attention surrounding psychedelics—could explain a good portion of the subjective improvements. This is data, not a reproach: this is how science is built, in phases, starting with what is small and safe before investing in large, controlled trials, which is exactly what the authors call for as the next step.
It is also worth remembering that none of this describes self-administration. What was evaluated was a complete intervention—controlled dose, clinical context, preparation, and psychological integration—and not the isolated substance. Outside of that framework, and given that this is a disorder with serious physical risks, extrapolating these results would be a mistake. Psilocybin remains a controlled substance in most countries; that is a legal fact that should be kept in mind without adding or subtracting value from what the research is showing. The reasonable conclusion is the most sober one: there is a door that deserves to be explored with rigor, without promising miracles or closing it out of prejudice.
Source
- Knatz Peck S, Shao S, Gruen T, Yang K, Babakanian A, Trim J, Finn DM, Kaye WH. Psilocybin therapy for females with anorexia nervosa: a phase 1, open-label feasibility study. Nature Medicine, 2023. DOI: 10.1038/s41591-023-02455-9
Educational content written from a harm reduction perspective and with respect for individual freedom. It is not a substitute for advice from a healthcare professional and is not intended to encourage or condemn any drug use.
