Because there are no proven treatments that normalize core symptoms in adult anorexia nervosa, a disorder with high chronicity, many individuals seek out alternative approaches to care. Recent evidence has suggested that anxiety, obsessive compulsive disorder, and diminished reward or motivation play key roles in the development and maintenance of dysfunctional eating, and poor outcome. In recent years, a growing number of studies have demonstrated the safety and preliminary efficacy of psilocybin in clinical trials for a range of psychiatric illnesses including treatment resistant depression, obsessive compulsive disorder, addiction, and anxiety. Psilocybin may represent a promising new treatment for anorexia nervosa. However, no studies have tested psilocybin in this eating disorder population. Accordingly, this study aims to establish the safety, tolerability and dosing of psilocybin in adult patients with anorexia nervosa, as well as gather pilot data on possible efficacy.~For this study, the investigators will recruit adults who currently have a DSM-V diagnosis of anorexia nervosa. Participants will undergo medical and psychological screening and those who are deemed eligible will partake in a maximum of 7 study visits, lasting from 4-8 weeks. On dosing day, participants will receive a single 25 mg dose of psilocybin along with psychotherapeutic support, which includes preparation and integration sessions surrounding the experience. There will be a follow-up period of one month following the psilocybin session during which a range of psychological measures (questionnaires and interviews) will be collected.
The primary aim of this study is to assess the safety and tolerability of one 25 mg dose of psilocybin in participants with anorexia nervosa based on adverse events (AEs), changes in vital signs, electrocardiograms (ECGs) and clinical laboratory tests. The secondary objectives are to explore the efficacy of a single 25 mg dose of psilocybin on eating disorder symptoms and behaviors, body image, anxiety, food related obsessions and rituals, and body weight.