Psilocybin or Ketamine for Alcohol Use Disorder: An Active Comparator Trial

Inclusion criteria: * Weight between 50kg and 150kg * No known allergies to rescue medication * For people capable of becoming pregnant, not pregnant and using contraception * Not currently breastfeeding * Meets criteria for DSM-V moderate to severe AUD. * Have at least 4 heavy drinking days (5 or more standard drinks in a day) in the past 30 days. * Not currently participating in formal treatment for AUD. * No history of a of cerebrovascular accident, asthma, or significant alcohol withdrawal history * No seizure disorder, coronary artery disease, heart failure, uncontrolled hypertension, insulin-dependent diabetes, pancreatitis, liver disease * No hallucinogen or ketamine use in past 12 months * No self-reported, personal, or familial history of specific psychotic disorders/episodes. * No serious traumatic brain injury (TBI) in the past 2 years * No substance use disorder other than AUD over the past 12 months * If taking a GLP-1 agonist, stable dosage for past 3 months * Family member/friend for pick-up, overnight post-drug session monitoring. * No MRI contraindications Exclusion Criteria: Drug/medication assessment that yields: nonprescription medication use, nutritional supplement, or herbal supplement (except when approved by the study investigators), medically unstable, current medication use that has significant potential to interact with study drug (e.g., antidepressants, antipsychotics, psychostimulants, treatments for addictions, other dopaminergic or serotonergic agents, lithium, anticonvulsants, or benzodiazepines). Psychiatric assessment that yields:1) history of severe suicide attempt, 2) current suicidality 3) first-degree relative with schizophrenia or schizoaffective disorder, 4) comorbid substance use disorder including cocaine, psychostimulant, or opioid use disorder within past 12 months 5) history of co-occurring psychotic episode/diagnosis including schizophrenia, schizoaffective disorder, schizophreniform, substance-induced psychosis, delusional disorder, or psychosis not otherwise specified, 6) high risk of adverse emotional or behavioral reaction based on the medical monitor's clinical evaluation that may also yield evidence of serious current stressors, a lack of meaningful social support, antisocial behavior, and/or serious personality disorders amongst other conditions. Medical assessment that yields: serious ECG abnormalities (evidence of ischemia, myocardial infarction, QTc prolongation \[QTc \> .045\]), serious abnormalities of complete blood count or chemistries, medical conditions that would preclude safe participation (significantly impaired liver function), or pregnancy. MRI contraindication (pacemaker, etc.)