Persisting Effects of Psilocybin

Inclusion Criteria:

- Have given written informed consent

- Have at least a high-school level of education or equivalent, and be fluent in English

- Be healthy and psychologically stable as determined by screening for medical and
psychiatric problems via a personal interview, a medical questionnaire, a physical
examination, an electrocardiogram (ECG), and routine medical blood and urinalysis
laboratory tests

- Agree to consume approximately the same amount of caffeine-containing beverage (e.g.,
coffee, tea) that he/she consumes on a usual morning, before arriving at the research
unit on the morning of the drug session day. If the participant does not routinely
consume caffeinated beverages, he/she must agree not to do so on the session day.

- Agree to refrain from using any psychoactive drugs, including alcoholic beverages and
nicotine, within 24 hours of each drug administration. The exception is caffeine.

- Agree not to take any "as needed" medications on the mornings of drug sessions

- Agree not to take sildenafil (Viagra®), tadalafil, or similar medications within 72
hours of each drug administration.

- Agree that for one week before each drug session, he/she will refrain from taking any
nonprescription medication, nutritional supplement, or herbal supplement except when
approved by the study investigators. Exceptions will be evaluated by the study
investigators and will include acetaminophen, non-steroidal anti-inflammatory drugs,
and common doses of vitamins and minerals.

- Have limited lifetime use of hallucinogens

Exclusion Criteria:

- Women who are pregnant (as indicated by a positive urine pregnancy test assessed at
intake and before each drug session) or nursing; women who are of child-bearing
potential and sexually active who are not practicing an effective means of birth
control.

- Cardiovascular conditions: coronary artery disease, stroke, angina, uncontrolled
hypertension, a clinically significant ECG abnormality (e.g., atrial fibrilation),
artificial heart valve, or stroke in the past year

- Epilepsy with history of seizures

- Insulin-dependent diabetes; if taking oral hypoglycemic agent, then no history of
hypoglycemia

- Currently taking psychoactive prescription medication on a regular (e.g., daily) basis

- Currently taking on a regular (e.g., daily) basis any medications having a primary
centrally-acting serotonergic effect, including mono-amine oxidase inhibitors (MAOIs).
For individuals who have intermittent or "as needed" use of such medications,
psilocybin sessions will not be conducted until at least 5 half-lives of the agent
have elapsed after the last dose.

- More than 20% outside the upper or lower range of ideal body weight according to
Metropolitan Life height and weight table

- Current or past history of meeting Diagnostic and Statistical Manual of Mental
Disorders, 5th edition (DSM-5) criteria for schizophrenia spectrum or other psychotic
disorders (except substance/medication-induced or due to another medical condition),
or Bipolar I or II Disorder

- Current or past history within the last 5 years of meeting DSM-5 criteria for a
moderate or severe alcohol or drug use disorder (excluding caffeine and nicotine)

- Have a first or second-degree relative with schizophrenia spectrum or other psychotic
disorders (except substance/medication-induced or due to another medical condition),
or Bipolar I or II Disorder

- Has a psychiatric condition judged to be incompatible with establishment of rapport or
safe exposure to psilocybin

- Head trauma

- Claustrophobia incompatible with scanning

- Cardiac pacemaker

- Implanted cardiac defibrillator

- Aneurysm brain clip

- Inner ear implant

- Prior history as a metal worker and/or certain metallic objects in the body -- must
complete magnetic resonance imaging (MRI) screening form and be approved by MRI
technologist before each scan