Psilocybin as a Novel Pharmacotherapy for Treatment-Refractory Anorexia Nervosa

This review (2021) appraises psilocybin as a novel pharmacotherapy for treatment-resistant anorexia nervosa (AN). It observes that classic psychedelics like LSD, 5-MeO-DMT, DMT, and psilocybin show a significant decrease in anxiety and depression-like symptoms, and lasting improvement in mental health. The review suggests that classic psychedelics, psilocybin in particular, show promise in normalizing dysfunctional neurobiological systems in AN and point towards a novel treatment intervention for treatment-resistant patients.


Anorexia Nervosa (AN) is a major health problem with one of the highest mortalities and treatment costs of any psychiatric condition. Cognitive behavioural therapy (CBT) is currently the most widely used treatment for AN in adults but provides remission rates ≤ 50%. Treatment drop-out is exceedingly high and those that persevere with treatment often relapse, causing increased risk of morbidity and mortality. There is an urgent need to find new interventions, especially as there are no approved pharmacological treatments for AN. Ideally, new treatments would target treatment-resistance and to decrease the chronicity associated with the disorder. Over the past two decades, emerging research into classic psychedelic substances (lysergic diethylamide acid (LSD), 5-Methoxy-N,N-Dimethyltryptamine (5-MeO-DMT), N,N-Dimethyltryptamine (DMT) and psilocybin), indicates that marked reductions in anxiety and depression-like symptoms, and lasting improvement in mental health, can follow from one or two exposures to these psychedelic substances. Anxiety and depression are the most prevalent co-morbid psychiatric symptoms in AN. Here we suggest that classic psychedelics, particularly psilocybin, have the potential to normalise dysfunctional neurobiological systems in AN and provide a novel treatment intervention that is worthy of consideration, particularly for treatment-resistant patients.

Authors: Sarah-Catherine Rodan, Phillip Aouad, Iain S. McGregor & Sarah Maguire


Eating disorders (EDs), of which anorexia nervosa is one, affect more than 8% of women during their lifetime and 2.2% of women each year. The number is lower for men, but still there more than 2% will be affected by an eating disorder during their lifetime. Those with EDs have severe pathological fear and anxiety around food, food, intake, and body weight. It’s common for those with EDs to also have symptoms of depression and anxiety disorders. Most worrying is that EDs are the category of mental health disorders with the highest mortality of any psychiatric illness.

It’s also so that many will live with an eating disorder for a long period of time. Of those suffering from an ED, 30% will live with it for more than 15 years. This is partly so because the current treatments don’t work. One way current treatments often break down is at the moment of success. If there is (much needed) weight gain, it’s in direct opposition to the deeply held belief or fear of those with EDs. The current paper discusses how psychedelic-assisted therapy, specifically with psilocybin, may help this patient population.

Three take-home messages

  • Psilocybin has been shown to be safe when used in a carefully controlled clinical setting
  • And it has been used successfully, in combination with talk therapy, in other refractory (treatment-resistant) mental health disorders such as PTSD and depression (TRD)
  • The unique long-term effects could indicate that it can help long-term and also reduce the burden on the healthcare system

At this time there are three research groups investigating psilocybin for EDs in phase I clinical trials. The studies will answer if, for this population, psychedelics can be a tool for improving mental health. The studies will also need to answer if they can assist in restoring weight to ‘normal’ levels and so also improving physical health.

The paper misquotes the number, or uses the prevalence number out of context, when saying that EDs affect 9% of the population. The closest number is 8.4% and that is lifetime prevalence for women.

Study details

Topics studied
Eating Disorders

Study characteristics
Literature Review