Clinical Research Directory

Inclusion Criteria: * Be a United States Military Veteran * Have at least a high-school level of education or equivalent (e.g. GED). * Have a current DSM-5 diagnosis of Post-traumatic Stress Disorder * Have a CAPS-5 total severity score of ≥23 at baseline * SSRIs will be allowable so long as participants are on a stable regimen for a period of 3 months. * Concurrent psychotherapy is allowed if the type and frequency of the therapy has been stable for at least 2 months prior to screening and is expected to remain stable during participation in the study. * Be medically stable as determined by screening for medical problems via a personal interview, a medical questionnaire, a physical examination, an electrocardiogram (ECG), and routine medical blood and urinalysis laboratory tests * No use of hallucinogens in the past 3 months and no history of regular or frequent use of hallucinogens Exclusion Criteria: * General medical exclusion criteria: * Individuals who are pregnant or nursing; individuals who are of child-bearing potential and sexually active who are not practicing a highly effective means of birth control * Individuals with partners of childbearing potential who are sexually active and not practicing a highly effective means of contraception * Cardiovascular conditions: coronary artery disease, stroke, angina, uncontrolled hypertension, a clinically significant ECG abnormality (e.g., atrial fibrilation), prolonged QTc interval (i.e., QTc \> 450 msec), artificial heart valve, or TIA in the past year • Systolic blood pressure (SBP) \> 139 mm HG; diastolic blood pressure (DBP) \> 89 mm HG; heart rate (HR) \> 90 bpm. * Epilepsy with history of seizures * Insulin-dependent diabetes; if taking oral hypoglycemic agent, then no history of symptoms of hypoglycemia * Psychiatric Exclusion Criteria: * Current or past history of meeting 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 history within six months of meeting DSM-5 criteria for a moderate or severe alcohol, tobacco, caffeine, or other drug use disorder; if a regular smoker, they must agree to use a nicotine patch on the day of dosing as smoking will not be allowed on these sessions * Have a first degree relative with schizophrenia spectrum or other psychotic disorders including substance/medication-induced or due to another medical condition * Risk for acute suicidality as determined by clinician judgment (C-SSRS) * Has a psychiatric condition which precludes the establishment of therapeutic rapport as evidenced by long-term patterns of unstable relationships, history of significant stress-related paranoia, and identity disturbances * History of a medically significant suicide attempt * Current MAOI antidepressant use