Could Psychedelics Transform Treatment for Eating Disorders?

In 2023, a clinical trial led by researchers from the University of California, San Diego (UCSD), explored the safety and therapeutic potential of psilocybin for anorexia nervosa (AN).

Now ,the team, led by Dr. Stephanie Knatz Peck, a clinical psychologist and associate clinical professor at the UCSD Eating Disorder Center, has provided an updated analysis and further details of the trial in an article published in Psychedelics – revealing first-hand experiences from the original 10 participants.

Anorexia nervosa is one of the most life-threatening psychiatric illnesses

Over 28 million Americans will suffer from an eating disorder in their lifetime. AN is a life-threatening psychiatric illnesses, defined by extreme weight loss, distorted body image and an intense fear of gaining weight. With the highest mortality rate among psychiatric disorders, ~5% of patients die within 4 years of diagnosis. Despite decades of research, many patients still struggle with lifelong symptoms even after intervention.

Traditional therapies, including cognitive-behavioral therapy, nutritional rehabilitation and pharmacological treatments, often have only limited success. In recent years, researchers have turned their attention to more unconventional methods, such as psychedelic medicine, in the search for more effective treatment avenues.

Psilocybin, the psychoactive compound present in psychedelic mushrooms, has gained attention for its benefcicial effects in treating a range of mental health conditions, such as depression, anxiety and addiction. Psilocybin acts on the serotonin system and can alter an individual's perception. Since changes in serotonin function have been implicated in anorexia, researchers believe that psilocybin treatment may help address aspects of the disorder untouched by conventional methods.

Assessing the safety of psilocybin in AN patients

The team’s original clinical trial was published in Nature Medicine. They conducted a phase 1, open-label feasibility study exploring the safety and potential therapeutic effects of psilocybin in adult women with AN or partial AN remission. The investigation involved ten participants, all diagnosed according to DSM-5 criteria. Each participant received a single 25 mg dose of synthetic psilocybin paired with structured psychological support before, during and after administration. 

No clinically significant changes were observed in critical markers such as electrocardiograms, vital signs or suicidality. Beyond safety outcomes, the trial highlighted the acceptability of psilocybin treatment among participants, many of whom described meaningful shifts in their psychological outlook.

Psilocybin treatment resulted in profound shifts in self-perception

In their Psychedelics article, the authors expand on their earlier investigations, using interviews and recollections of first-hand experiences from the participants.

A majority (90%) rated the psilocybin session as one of the five most meaningful experiences of their lives, with many claiming profound shifts in self-perception and life priorities. Quantitative measures indicated that 40% of participants achieved clinically significant reductions in eating disorder psychopathology by the 3-month follow-up. Participants who responded to the treatment reported transformative changes in their relationship with their bodies and eating behaviors.

“What's particularly interesting is that 60% of participants reported a reduction in the importance of physical appearance, while 70% noted quality-of-life improvements and shifts in personal identity,” said Peck.

In the follow-up sessions, many of the participants described feeling a dissociation from the eating disorder’s centrality to their identity.

“Before I participated, my anorexia was the most important relationship in my life that came before friends, family or partners and everything. I was valuing weight as the number one focus in my life. But during the psilocybin experience, I was able to see sort of the insignificance and it seemed so trivial after the experience. It just seemed trivial for me to focus my life around weight when there were so many other important factors,” one participant said.

Changes in outlook did not always translate to weight restoration

Although the findings were promising, the study also revealed a variability in treatment response. Changes in psychological outlook didn't automatically translate to weight restoration, and improvements in weight were modest and inconsistent across the cohort.

When asked about this disparity, one participant said: “When you ask me questions about my weight and why it hasn’t changed, it feels like you are only basing my recovery on weight and that feels bad since I feel like I no longer have an eating disorder. The irony is that now that I want to recover, I can eat intuitively, but that is not enough to support physical recovery. Things might not look that different from the outside, but they feel completely different from the inside.”

Complimenting existing treatment plans with psilocybin

“Our findings suggest that psilocybin may be helpful in supporting meaningful psychological change in a subset of people with anorexia nervosa,” said Peck.

The study calls for further research to fully understand the variability in response and optimize treatment outcomes. While psilocybin appears to facilitate profound attitude shifts for some participants, the lack of consistent behavioral and physical recovery metrics, suggests that psilocybin alone may not suffice as a standalone treatment.

The article notes one area of future exploration involves the role of genetic factors, specifically variations in the 5HT2A receptor. Given the receptor’s centrality to psilocybin’s mechanism of action and evidence that some individuals with AN exhibit reduced 5HT2A activity, further research is needed to investigate how these variations may influence treatment outcomes.

This research represents an important step toward understanding how psilocybin therapy may complement existing treatment plans for AN.

Reference: Peck SK, Fisher H, Kim J, Shao S, Trim J, Kaye WH. Psychedelic treatment for anorexia nervosa: A first-hand view of how psilocybin treatment did and did not help. Psychedelics. 2024. doi: 10.61373/pp024e.0034

This article is a rework of a press release issued by Genomic Press. Material has been edited for length and content.