Exploratory Study of Low Dose Psilocybin

Individuals who call research staff will undergo an initial telephone screen that will determine eligibility.

Week 1: Baseline Intake Appointment. Those who are eligible to participate on the basis of the telephone screen and provide informed consent will then complete a standard demographic questionnaire, a detailed psychiatric interview, and provide a urine sample for confirmation of substance abstinence and pregnancy status. Participants will then be administered a detailed medical history interview and physical examination including EKG and blood panel.

Week 2: Orientation. Participants who are medically eligible to participate will be scheduled for a psychoeducational orientation session that further explains the rationale of the study, and summarizes the study logistics. Participants will complete a number of baseline questionnaires and neuropsychological assessments at this time.

Week 3: Drug administration #1. In a between-groups design, participants will be randomized to receive 0 mg, 1 mg, 2.5 mg, or 5 mg of psilocybin at five weekly 6-hour long drug administration sessions. Dose will remain constant for each participant at each drug administration session.

At Drug Administration #1 and all subsequent drug administration sessions, participants will complete visual analogue scale (VAS) questions drawn from different sources that include drug abuse liability measures. These VAS questions will be administered at drug administration baseline and every 30 minutes thereafter through the end of acute effects at 6-hrs post-baseline. Research staff will complete a number of observational assessments at similar intervals.

Blood pressure will be assessed at regular intervals via automatic blood pressure monitor (i.e., at baseline and at 30, 60, 90, 120, 180, 240, and 360 min post-baseline), and medication for the treatment of acute hypertension will be administered should blood pressure exceed 200 systolic and/or 110 diastolic.

At peak drug effects (2 hr post-baseline), a number of measures will be administered, each differing by drug administration session. At Drug Administration #1, participants will undergo two electroencephalogram (EEG) tasks (with assessments at baseline serving as pre-drug control values).

At 6-hr post-baseline, participants will complete self-report measures assessing the subjective experience. These questionnaires will be administered at the conclusion of each drug administration session. Participants will then be administered a brief semi-structured qualitative interview designed to probe the nature of their experience. All participants will be required to arrange for transportation home from the CRU; participants will not be allowed to drive themselves after drug administration sessions.