Trial Outcomes & Findings for Visual Surround Suppression and Perceptual Expectation Under Psilocybin (NCT NCT04424225)
NCT ID: NCT04424225
Last Updated: 2025-06-27
Results Overview
No surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. .
TERMINATED
PHASE1
10 participants
3 hours after dose 1
2025-06-27
Participant Flow
Participant milestones
| Measure |
Psilocybin First, Niacin Second
Participants in this arm will receive psilocybin first, then niacin
Psilocybin: 25 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
Niacin: 100 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
|
Niacin First, Psilocybin Second
Participants in this arm will receive niacin first, then psilocybin
Psilocybin: 25 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
Niacin: 100 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
|
|---|---|---|
|
Overall Study
STARTED
|
6
|
4
|
|
Overall Study
COMPLETED
|
4
|
3
|
|
Overall Study
NOT COMPLETED
|
2
|
1
|
Reasons for withdrawal
Withdrawal data not reported
Baseline Characteristics
Visual Surround Suppression and Perceptual Expectation Under Psilocybin
Baseline characteristics by cohort
| Measure |
Psilocybin First, Niacin Second
n=6 Participants
Participants in this arm will receive psilocybin first, then niacin
Psilocybin: 25 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
Niacin: 100 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
|
Niacin First, Psilocybin Second
n=4 Participants
Participants in this arm will receive niacin first, then psilocybin
Psilocybin: 25 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
Niacin: 100 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)
|
Total
n=10 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Categorical
<=18 years
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Age, Categorical
Between 18 and 65 years
|
6 Participants
n=5 Participants
|
4 Participants
n=7 Participants
|
10 Participants
n=5 Participants
|
|
Age, Categorical
>=65 years
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Age, Continuous
|
35.7 years
STANDARD_DEVIATION 9.2 • n=5 Participants
|
34.8 years
STANDARD_DEVIATION 3.2 • n=7 Participants
|
35.3 years
STANDARD_DEVIATION 7.1 • n=5 Participants
|
|
Sex: Female, Male
Female
|
3 Participants
n=5 Participants
|
1 Participants
n=7 Participants
|
4 Participants
n=5 Participants
|
|
Sex: Female, Male
Male
|
3 Participants
n=5 Participants
|
3 Participants
n=7 Participants
|
6 Participants
n=5 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Asian
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Black or African American
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
White
|
4 Participants
n=5 Participants
|
3 Participants
n=7 Participants
|
7 Participants
n=5 Participants
|
|
Race (NIH/OMB)
More than one race
|
2 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
2 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=5 Participants
|
1 Participants
n=7 Participants
|
1 Participants
n=5 Participants
|
PRIMARY outcome
Timeframe: 3 hours after dose 1No surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. .
Outcome measures
| Measure |
Psilocybin
n=3 Participants
Received Psilocybin
|
Niacin
n=3 Participants
Received Niacin
|
|---|---|---|
|
Psychophysical Descrimination Threshold - No Surround Suppression (NS) Dose 1
|
.4849 percent contrast
Standard Deviation .11731
|
.499 percent contrast
Standard Deviation .04398
|
PRIMARY outcome
Timeframe: 3 hours after dose 2No surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. .
Outcome measures
| Measure |
Psilocybin
n=3 Participants
Received Psilocybin
|
Niacin
n=3 Participants
Received Niacin
|
|---|---|---|
|
Psychophysical Descrimination Threshold - No Surround Suppression (NS) Dose 2
|
.4756 percent contrast
Standard Deviation .11254
|
.4772 percent contrast
Standard Deviation .04711
|
PRIMARY outcome
Timeframe: 3 hours after dose 1Orthogonal surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Orthogonal surround suppression condition (OS).
Outcome measures
| Measure |
Psilocybin
n=3 Participants
Received Psilocybin
|
Niacin
n=3 Participants
Received Niacin
|
|---|---|---|
|
Psychophysical Descrimination Threshold - Orthogonal Surround Suppression (OS) Dose 1
|
.3841 percent contrast
Standard Deviation .17284
|
.4491 percent contrast
Standard Deviation .06183
|
PRIMARY outcome
Timeframe: 3 hours after dose 2Orthogonal surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Orthogonal surround suppression condition (OS).
Outcome measures
| Measure |
Psilocybin
n=3 Participants
Received Psilocybin
|
Niacin
n=3 Participants
Received Niacin
|
|---|---|---|
|
Psychophysical Descrimination Threshold - Orthogonal Surround Suppression (OS) Dose 2
|
.4678 percent contrast
Standard Deviation .12891
|
.4261 percent contrast
Standard Deviation .03799
|
PRIMARY outcome
Timeframe: 3 hours after dose 1Parallel surround suppresion condition for visual psychophysics tasks consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Parallel surround suppression condition (PS). .
Outcome measures
| Measure |
Psilocybin
n=3 Participants
Received Psilocybin
|
Niacin
n=3 Participants
Received Niacin
|
|---|---|---|
|
Psychophysical Descrimination Threshold - Parallel Surround Suppression (PS) Dose 1
|
.3015 percent contrast
Standard Deviation .18275
|
.3988 percent contrast
Standard Deviation .10744
|
PRIMARY outcome
Timeframe: 3 hours after dose 2Parallel surround suppresion condition for visual psychophysics tasks consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Parallel surround suppression condition (PS). .
Outcome measures
| Measure |
Psilocybin
n=3 Participants
Received Psilocybin
|
Niacin
n=3 Participants
Received Niacin
|
|---|---|---|
|
Psychophysical Descrimination Threshold - Parallel Surround Suppression (PS) Dose 2
|
.4195 percent contrast
Standard Deviation .13829
|
.3672 percent contrast
Standard Deviation .06696
|
Adverse Events
Psilocybin
Niacin
Serious adverse events
Adverse event data not reported
Other adverse events
| Measure |
Psilocybin
n=9 participants at risk
Received Psilocybin
|
Niacin
n=8 participants at risk
Received Niacin
|
|---|---|---|
|
General disorders
BackPain
|
11.1%
1/9 • Number of events 1 • Week 12
|
12.5%
1/8 • Number of events 1 • Week 12
|
|
General disorders
Headache
|
44.4%
4/9 • Number of events 7 • Week 12
|
12.5%
1/8 • Number of events 1 • Week 12
|
|
General disorders
sleep disturbance
|
22.2%
2/9 • Number of events 2 • Week 12
|
12.5%
1/8 • Number of events 3 • Week 12
|
|
General disorders
stomach pain
|
22.2%
2/9 • Number of events 2 • Week 12
|
25.0%
2/8 • Number of events 2 • Week 12
|
|
General disorders
Nausea
|
33.3%
3/9 • Number of events 4 • Week 12
|
0.00%
0/8 • Week 12
|
|
General disorders
Emotional
|
22.2%
2/9 • Number of events 3 • Week 12
|
0.00%
0/8 • Week 12
|
|
General disorders
Fatigue
|
11.1%
1/9 • Number of events 1 • Week 12
|
0.00%
0/8 • Week 12
|
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place