Psilocybin-Assisted Therapy for Treatment-Resistant Depression in Bipolar II Disorder

Inclusion Criteria: 1. You are male or female aged 19 to 65 years inclusive. 2. You have a diagnosis of bipolar disorder type II, and are currently in a major depressive episode. 3. You are willing, for the entire duration of the study, to practice highly effective methods of contraception (e.g., contraceptive pills, intrauterine device or system, vasectomy and tubal ligation, or double-barrier methods of contraception) OR agree to completely abstain from heterosexual intercourse. Females who do not have childbearing potential are required to be postmenopausal for at least 1 year before the screening visit (confirmed by an FSH test) OR surgically sterile. 4. You have sufficient English language skills to understand, consent to, and comply with study requirements, study visits, and to return to the clinic for follow-up evaluations. 5. Your current medications have been at a stable dose for two weeks prior to the dosing visit. Exclusion Criteria: 1. You have a history of psychotic symptoms. 2. You have a history of seizures. 3. You have a first-degree relative, such as your parent, sibling, or child, with a diagnosis of a primary psychotic disorder (e.g., schizoaffective disorder, schizophrenia). 4. You have a current unstable or inadequately treated medical illness, especially cardiovascular illness, except for the current depression. 5. You recently (i.e., within the past 6 weeks) started taking treatment for your acute bipolar depressive episode. 6. You recently (i.e., within the past 8 weeks) began structured psychotherapy (e.g., cognitive-behavioral therapy, interpersonal psychotherapy, family-focused therapy, or interpersonal and social rhythm therapy). 7. You have a history of nonresponse or intolerance to psilocybin. 8. You have, in the past 6 months, used any psychedelic drugs, including ketamine, LSD, or psilocybin-containing mushrooms. 9. You have a history of non-response to electroconvulsive therapy. 10. You are pregnant or lactating.