Anorexia nervosa is one of the hardest psychiatric conditions to treat. It has the highest mortality rate of any mental illness, existing treatments help fewer than a third of patients long-term, and for people who’ve been living with it for years, the usual talk therapies often stop working. So when a new study out of Imperial College London reports that psilocybin, the active compound in magic mushrooms, might offer a way in where other treatments haven’t, it’s worth paying attention.
The study, published today in the British Journal of Psychiatry, is small and preliminary (this is what researchers call a “pilot study,” basically a first test run before the bigger trials happen). But the results are encouraging enough that they’re already fueling calls for larger studies.
The study
Researchers recruited 21 women with long-standing anorexia nervosa (on average they’d been ill for almost 11 years) and gave each of them three doses of synthetic psilocybin over six weeks. The doses followed a fixed pattern: a tiny 1mg “starter” dose, then two full 25mg doses, each two weeks apart. Every dosing day was wrapped in therapy sessions before and after, and participants kept working with their existing eating disorder teams throughout.
Participants went through video screening, in-person psychiatric assessments, and had a support person (a friend or family member) involved throughout. Most had to come off antidepressants first, since SSRIs can dull the psychedelic effect.
The results
The headline result is that eating disorder symptoms, measured using a standard clinical interview, dropped significantly and stayed lower for six months after treatment. Participants also showed real gains in motivation, meaning they moved from denying the seriousness of their illness toward actually wanting to change, which matters enormously in anorexia, where the illness often feels like part of a person’s identity rather than something foreign to fight.
By the three month mark, nearly half of participants had scores that fell within a healthy “community norm” range. That’s a huge shift for a group who’d already tried and failed at existing treatments.
Interestingly, the researchers couldn’t tell which of the three doses drove the improvement most. Even the tiny 1mg starter dose seemed to have some benefit, similar to the two full doses. That’s a puzzling finding, and the authors suspect the therapy and support surrounding the dosing sessions, not just the psilocybin itself, may be doing a lot of the work.
Safety
Retention was excellent (over 95% of participants completed the study, against dropout rates of 20 to 70% typically seen in eating disorder treatment). The most common side effects were headaches and nausea, both mild and short-lived.
There is one serious detail worth being upfront about: one participant attempted suicide twice, seven and nine months after the study ended. Researchers assessed these events as unlikely to be related to the psilocybin itself, but they’re reported transparently in the paper. It’s a sober reminder that anorexia carries real and ongoing risk, psilocybin trial or not, and that recovery is rarely linear.
Foundation
The researchers are careful not to overclaim. This was a small, single-arm study (meaning everyone got the drug, there was no placebo comparison group), the participants were overwhelmingly white, highly educated, and female, and the improvement varied a lot from person to person. Some people did really well; others barely shifted.
What this study does establish is feasibility that people with severe, treatment-resistant anorexia can safely go through a structured psilocybin therapy protocol, stick with it, and in many cases benefit. That’s the groundwork larger, properly controlled trials need before anyone can say psilocybin actually treats anorexia rather than simply appearing to help alongside everything else going on in a person’s recovery.
Several bigger trials are already underway, so this likely won’t be the last word on the subject.
Keep up with the research here.
