Table 1.
Data regarding trial design, sample size, diagnostic group, prior psychedelic use, expectancy and alliance, allocation concealment, protocol, and SAP.
| Study | Design | Sample size (n randomized) | Diagnostic group | Intervention/control | Prior psychedelic use (% use) | Expectancy/therapeutic alliance | Allocation concealment (correct guesses) | Protocol/SAP |
|---|---|---|---|---|---|---|---|---|
| Moreno et al. (2006) | WSD | 9 (−) | OCD | Psilocybin/psilocybin (LD) a | (100%) | −/− | − | −/− |
| Grob et al. (2011) | WSD | 12 (−) | C-R anxiety disorders | Psilocybin/niacin a | (67%) | −/− | Reported narratively as unsuccessful | −/− |
| Gasser et al. (2014) | PGD | 12 (12) | Life-threatening illness and an anxiety disorder | LSD/LSD (LD) a | (8%) d | −/− | Participants (100%) Study staff (92%) e |
−/− |
| Griffiths et al. (2016) | C | 51 (56) | C-R anxiety and depression disorders | Psilocybin/psilocybin (LD) a | (45%) | −/− | Reported narratively as unsuccessful | −/− |
| Ross et al. (2016) | C | 29 (31) | C-R anxiety and depression disorders | Psilocybin/niacin a | (55%) | −/− | Participants − Study staff (97%) |
+/+ |
| Palhano-Fontes et al. (2019) | PGD | 29 (35) | TR unipolar major depressive disorder | Ayahuasca/placebo liquid b | (0%) | −/− | Participant (81%)
f
Study staff − |
−/− |
| Carhart-Harris et al. (2021) | PGD | 59 (59) | Moderate-to-severe major depressive disorder | Psilocybin + microcrystalline c /psilocybin (LD) a + escitalopram | (92%) | −/+ | − | +/+ |
| Bogenschutz et al. (2022) | PGD | 95 (95) | Alcohol use disorder | Psilocybin/diphenhydramine c | − | −/− | Participant (94%) Study staff (93%) |
+/+ |
| Holze et al. (2022) | WSD | 39 (44) | C-R or generalized anxiety disorders | LSD in ethanol/solely ethanol c | − | −/− | Participants in active group (95%) Study staff – |
−/− |
| Goodwin et al. (2022) | PGD | 233 (233) | Moderate-to-severe major TR depressive disorder | Psilocybin/psilocybin (LD) a | (6%) | −/− | − | +/+ |
WSD: within-subjects design; PGD: parallel group design; C: crossover; SAP: statistical analysis plan; C-R: cancer related; OCD: obsessive-compulsive disorder; TR: treatment resistant; LD: low dose; LSD: lysergic acid diethylamide; Study staff: could be therapists, raters, or other investigators; “–”: no reporting; “+”: reported.
a
Active placebo.
b
Nausea inducing placebo liquid (water, yeast, citric acid, zinc sulfate, and caramel colorant).
c
Inactive placebo.
d
Only assessed prior LSD use.
e
Staff guessed wrong at one of two placebo administrations for a single patient.
f
Data missing for two patients.