Psilocybin Therapy for Symptoms After Concussion

In order to be eligible to participate in this study, an individual must meet all of the following criteria: * Individuals of all sexes, gender identities, and ethnicities * Ages 18 to 65 years at the time of screening * Diagnosis of concussion based on the 2024 ACRM criteria * Meet ICD-10 criteria for PSaC for at least 3-months to a maximum of 5 years * Have an overall RPQ score ≥ 13 with 3 or more symptoms scored ≥3 * Limited lifetime use of serotonergic hallucinogens * Ability to read/write English An individual who meets any of the following criteria will be excluded from participation in this study: * Severe or moderate substance use disorder other than nicotine in past 6 months * Lifetime diagnosis of schizophrenia or bipolar disorders (or first or second-degree relative) * Active suicidal ideation or serious attempt within the past 1 year. * Current pregnancy or nursing, trying to become pregnant * Any notable abnormality on ECG or routine medical blood laboratory test * Insulin-dependent diabetes; if taking oral hypoglycemic agent, then no history of hypoglycemia * Epilepsy with a history of seizures * Current or recent (within 12 weeks) participation in a clinical trial * Cognitive impairment (SLUMS score \<20) * Suffered a moderate/severe TBI at least once in lifetime * Any other circumstances that, in the opinion of the investigators, compromises participant safety