How Psilocybin Therapy Can Offer New Hope for Individuals Living with Anorexia Nervosa
By Hannah Douglass and Meg Vardy (nee Spriggs), Imperial College London
We recently published a new study, which investigated whether psilocybin therapy could help people living with anorexia nervosa (AN), and we reported promising results.
What is anorexia nervosa and why is it so difficult to treat?
AN is a serious eating disorder (ED) which affects up to 4% of females and 0.3% of males in their lifetimes. People living with this condition experience an overwhelming urge to limit their food intake, which for some can result in very low body weight.
Individuals with AN are often regarded as having low motivation to engage in treatment, or “resistant” to recovery. This is because AN often develops as a coping mechanism which individuals rely on to function, and therefore, can become a defining feature of their personality and selfhood. People living with AN are often unable to recognise the severity of their condition or the negative impact it has on their well-being and others around them (in their eyes, the positives often outweigh the negatives), making treatment challenging. Therefore, exploring new treatments that target motivation is critically important.
Current treatment options, such as talking therapies or antidepressants, may help with co-occurring depression and anxiety, but often provide little benefit to improving AN symptoms. Relapse rates following treatment are very high, and approximately 20-30% will live with the condition for the majority of their lives.
A new study investigated psilocybin therapy as a potential new treatment
When combined with therapy or psychological support, psilocybin (the active ingredient in magic mushrooms) has been shown to improve symptoms for people living with different mental health conditions, particularly depression. It is thought that psilocybin induces a state of “hyperplasticity” within the brain, which can facilitate longer-lasting psychological flexibility. When this flexibility is combined with the relevant external support, individuals may be able to engage more openly in treatment or make behavioural changes that were previously too challenging. This effect could be particularly important for AN, as the condition is characterised by rigid and ingrained thought patterns and behaviours.
In 2023, a small study in the USA reported that AN symptoms were improved for up to 3 months following psilocybin therapy. It also found the treatment to be safe and feasible, which is important given the physical vulnerability of this patient group and known resistance to engaging in treatment. However, these results were only based on 10 females receiving one high-dose (25 mg) psilocybin session with only brief accompanying therapy, so replication in a larger study was required to further assess this treatment for AN.
Our new study published in The British Journal of Psychiatry investigated this treatment further in 21 females. All participants received three psilocybin therapy sessions, two with a high dose (25 mg), and one with a very low “placebo” dose (1 mg). The placebo was intended to be an ineffective dose we could compare to the other active sessions. The therapy involved working with two “therapists” (which included psychologists, psychiatrists, and experienced psychedelic guides) through pre-dosing preparation, dosing, and post-dosing integration, totalling ~50 hours of therapeutic support.
What did we find?
Safety and feasibility
Although all participants experienced some form of side effect, the majority were mild (e.g., headache, nausea during the acute drug effect). Overall, this treatment was safe.
Nearly half of participants were withdrawn from antidepressant medication prior to taking part in the study. This did not impact clinical change. One participant attempted suicide twice over 6 months after the study; however, this was unrelated to the treatment. This indicates the importance of safety monitoring in clinical psychedelic research.
We met our recruitment target and 95.2% of participants remained in the study, indicating that the treatment was feasible in this group.
Treatment outcomes
Eighteen out of the 20 (90%) participants who completed all dosing sessions reported an improvement in the severity of their AN symptoms two weeks after completing treatment, which, for some, was sustained for the entire follow-up period of 12 months. Of the 19 participants who were still in the study at 12 months, 11 (58%) reported at least a 0.5-point improvement in their AN severity score (on a scale of 0 – 6). Symptom improvements were seen across dietary restraint and concerns about food, their weight and their body.
Participants also reported feeling more motivated to engage in change in relation to their eating disorder. This improved motivation related to:
An improved ability to recognise and acknowledge the severity of their disorder and reporting greater readiness to engage in change. The average symptom score improved by 31% at 3 months and by 26% at 12 months.
An elevated desire to recover for themselves rather than for others around them. The average symptom score improved by 15% at 3 months and by 12% at 12 months.
Greater confidence in themselves that they can change. The average symptom score improved by 41% at 2 months and by 18% at 12 months.
The degree of improvement across participants varied, indicating that this treatment was more beneficial for some than others.
We didn’t see any difference in the effect of the placebo dose and the high doses. This could mean that extensive therapy was sufficient to improve individuals’ symptoms. However, as the placebo dose (1 mg) was given first, we can’t know whether the short-term improvement we saw after this dose would have lasted for 12 months.
What these results mean
Our participants had lived with AN for an average of 11 years and found previous treatments to be unsuccessful in maintaining remission. The significant improvements reported indicate that for this small group of females with long-standing AN, psilocybin therapy was feasible, safe, and potentially beneficial. These results support further investigation of psilocybin therapy as a treatment for AN, particularly with larger and more diverse groups.
What these results don’t mean
These findings do not prove that psilocybin therapy is a cure for AN or other types of eating disorders. Whilst these results offer hope to people living with AN, this is only the second study ever conducted investigating psilocybin therapy as a treatment for AN. Across the two research studies, only 31 females who met very strict inclusion criteria received this treatment. Neither of these studies meets the gold-standard criteria of a randomised controlled trial (RCT).
Importantly, this research was conducted using synthetic (lab-made) psilocybin in clinical settings with oversight from medical doctors and with substantial psychological support; therefore, these settings do not match those of recreational psychedelic use or therapeutic use outside of a research setting.
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How we move forward from here
This research is a starting point, not the end point, to understanding whether psilocybin therapy could be an effective treatment avenue for people with AN. More research is needed on AN and other eating disorders, and is already underway in Australia, the US, the UK, and other countries.
Over the next decade, we will get a much clearer picture of how psilocybin works in the brain, what the most effective treatment model is, who this treatment might work for, and the potential of psilocybin and other psychedelics as a treatment for eating disorders.
A message from the authors to those living with an eating disorder
If you can take anything from this new study, please take hope. There are many people dedicating their lives to improving support and treatment for those living with eating disorders. With lived experience of AN ourselves, we know how scary and isolating it can be. Recovery can be scary, but it is also possible. When you are ready, there are people ready to help and support you.
Leading this study was a pivotal step in Dr Meg Vardy’s own recovery and her understanding of the importance of compassion and hope for healing. For those in Aotearoa New Zealand, Meg founded the first peer-support eating disorder charity in the country, JourneyED.
You are worthy of support and a life of freedom.