A recent pilot study suggests that psilocybin, the active compound in “magic mushrooms,” provides evidence of safety and potential psychological benefits for adult women with anorexia nervosa when paired with extensive talk therapy. The findings indicate that this combined approach might help reduce eating disorder symptoms and increase a patient’s internal motivation to recover. The research, which offers a possible new avenue for a condition that is notoriously difficult to treat, was published in The British Journal of Psychiatry.
Anorexia nervosa is a psychiatric condition characterized by a severe restriction of food intake, an extreme fear of gaining weight, and a distorted perception of body shape. It has one of the highest mortality rates among all psychiatric conditions and frequently becomes intertwined with a person’s sense of identity. This integration into a person’s identity often makes the disorder highly resistant to conventional psychological interventions. Up to 30 percent of diagnosed individuals develop a chronic version of the illness that does not respond to standard care.
Because existing treatments often fail, scientists have started exploring alternative pharmacological approaches, including psychedelic substances. Psilocybin is a naturally occurring compound that interacts with serotonin receptors in the brain to produce altered states of consciousness. Recent systematic reviews of the literature by Francesco Bevione and colleagues highlighted that early, small-scale trials and case studies have provided evidence that psilocybin is generally safe for people with eating disorders.
Animal models have also provided insights into how this drug might operate in the brain. Research led by Claire J. Foldi demonstrated that psilocybin helped female rats subjected to an anorexia model maintain their body weight and improve their cognitive flexibility, which is the ability to adapt to new rules and environments.
This animal research indicated that the drug alters the expression of specific serotonin receptors in the brain, particularly the 5-HT1A and 5-HT2A receptors. However, related studies on mice suggest that psilocybin’s physiological effects, such as its impact on immune system inflammation, depend heavily on an animal’s physical state and environment.
To build on this preliminary data, a team of researchers from the Centre for Psychedelic Research at Imperial College London designed a pilot study to test the intervention in humans. The research was led by Hannah M. Douglass alongside Robin L. Carhart-Harris. They aimed to assess the safety, feasibility, and potential psychological benefits of psilocybin therapy in a group of adult women who had not responded to traditional anorexia treatments.
The researchers recruited 21 female participants between the ages of 23 and 52 who had a primary diagnosis of anorexia nervosa for at least three years. On average, the participants were 32 years old, had lived with the disorder for about 11 years, and had an average Body Mass Index (BMI) of 16.4. A healthy BMI is generally considered to be 18.5 or higher. The participants had not found long-term success with previous treatments.
The study utilized a single-blind, within-individual design, meaning there was no separate control group that received a placebo for the entire study. Over a six-week period, all 21 women attended three dosing sessions. They received a 1-milligram dose of psilocybin first, which was intended to be so low that it acted as a placebo. This was followed by two 25-milligram doses, spaced two weeks apart. Participants knew they were receiving psilocybin but did not know the dosage order.
Each dosing session took place in a supportive environment and was flanked by extensive preparation and integration talk therapy. Ten of the participants were required to withdraw from antidepressant medications, such as selective serotonin reuptake inhibitors (SSRIs), to prevent these drugs from blunting the psychedelic experience. The researchers monitored the participants’ safety, physical health, and psychological symptoms at multiple time points up to a year after the final session.
To measure eating disorder severity, the researchers primarily used the Eating Disorder Examination (EDE) interview, which involves a clinician assessing the patient’s symptoms. The participants had an average baseline EDE score of 3.2. The research team also used the Readiness and Motivation Questionnaire (RMQ) to track the participants’ self-reported motivation to recover.
The administration of psilocybin was well tolerated by the participants. All 21 women experienced at least one adverse event, but most were mild to moderate in severity. The most common side effects were transient headaches, reported by about 37 percent of participants, and nausea, reported by 25 percent. The study did not track BMI for the full year, but during the initial six weeks, the researchers noted no meaningful change in the participants’ body weight.
The clinician-administered assessments indicated that eating disorder symptoms decreased over time. The average global EDE score dropped by approximately 1.08 points by the final six-week visit. This reduction represents a massive relative drop from the 3.2 baseline score, yielding a large effect size. These improvements were generally sustained, with a 0.98-point reduction maintained at the six-month follow-up. Nearly all participants showed some level of improvement two weeks after the final session.
By the three-month mark, almost half of the participants had achieved symptom scores that fell within the range of a normal community population without an eating disorder. The researchers noted that individuals with a higher severity of symptoms at the start of the study tended to experience greater overall reductions in their scores. When analyzing the data, the scientists controlled for the potential impact of antidepressant withdrawal, finding that this variable did not alter the main outcomes.
The participants also self-reported changes in their mindset. The participants’ precontemplation scores on the RMQ decreased, indicating that their motivation to recover increased after the first 25-milligram dose. This shift toward wanting to change was sustained across the 12-month follow-up period. When comparing symptom reduction between the different dosage days, the differences were not statistically significant, indicating that the overall treatment package contributed to the psychological shifts rather than one specific dose.
Douglass, who led the study while completing her PhD at Imperial College London, reflected on the clinical outcomes. “This study delivered a brief program of psilocybin dosing and therapeutic support over a six-week period,” Douglass said. “Our results in individuals living with anorexia nervosa are encouraging, especially given that these participants had found previous treatments unsuccessful in maintaining their remission. However, further research is needed to assess how these findings might apply to a broader, more diverse population.”
The trial’s retention rate was 95.2 percent, with only one participant choosing to withdraw after the second dose due to the emotional and time commitments. Professor Robin Carhart-Harris, the senior author and trial designer, highlighted this particular success.
“This was a pioneering trial with promising results that justify larger and more rigorous studies,” Carhart-Harris said in a news release. “In particular, the retention rate was excellent, something that is often a real challenge in anorexia nervosa treatment. This was despite the considerable commitment required from participants involving day-long dosing sessions and several sessions of psychotherapy.”
The therapeutic context was an essential element of the intervention. Jennifer Danby, the lead therapist on the trial, noted how the psychedelic experience appeared to open new psychological doors for the patients.
“Having worked in the field of eating disorders for over 15 years it was encouraging to see that the trial, albeit with a very small cohort, provided an opportunity for individuals living with anorexia nervosa to approach treatment from a different angle,” Danby said. “Anorexia often serves as a protective mechanism for people and we saw participants be able to explore their relationship with the illness and gain some new perspectives. By laying fertile ground for change, even minor adjustments can lead to promising change longer term.”
David Erritzoe, another key researcher on the team, cautioned against treating the drug as a standalone cure. “The findings bear out further research, but it’s important to note that this was a particular dosing model carefully designed to support vulnerable participants with extensive psychological therapy alongside the psychedelic treatment,” Erritzoe said. “To be effective and safe, psychedelic treatments for individuals with complex mental health presentations, such as anorexia nervosa, should be given by trained clinicians in a supportive environment.”
The absence of a separate, drug-free control group makes it impossible to definitively attribute the observed psychological improvements to the psilocybin itself. Participants received roughly 50 hours of therapeutic contact during the six-week study. This intensive psychological support, combined with the natural passage of time, may have driven the reductions in eating disorder symptoms. A randomized controlled trial is necessary to separate the chemical effects of the drug from the benefits of the accompanying psychotherapy.
The study’s participants were relatively homogenous. The majority were highly educated white women. This demographic profile does not represent the full spectrum of individuals who suffer from eating disorders. The strict eligibility requirements also resulted in a sample of people who might have had more stable home environments or greater cognitive reserves, which can facilitate better therapeutic engagement. As a result, these findings cannot be readily generalized to a broader or more diverse population.
There was also a high degree of variation in how well the participants maintained their symptom improvements over the long term. Some individuals experienced a return of their eating disorder thoughts and behaviors during the one-year follow-up period. This variation indicates that psilocybin therapy might not induce permanent shifts for everyone and that post-study life events play a major role in long-term recovery.
During the follow-up period, one participant attempted suicide on two occasions. The study doctors and an independent safety board assessed these events and concluded they were unlikely to be related to the psilocybin intervention, given that they occurred seven and nine months after the final dosing session. These events highlight the elevated baseline risk of suicidality in populations with severe anorexia nervosa and the absolute necessity of rigorous clinical monitoring in psychiatric research.
The study, “Psilocybin therapy for adult females with anorexia nervosa: pilot study,” was authored by Hannah M. Douglass, Meg J. Spriggs, Kate Godfrey, Jennifer L. Danby, Frederico J. C. de Magalhaes, Lauren Macdonald, Kirsty L. Alderton, Stephanie Archer, Kirran Ahmad, Jonny Martell, Jennifer T. Frias, Gabriela Sawicka, Tim Read, Allan Blemings, Adele Lafrance, Dasha Nicholls, David Erritzoe, Rebecca J. Park, David J. Nutt, and Robin L. Carhart-Harris.
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