Table 2.
Summary of clinical studies evaluating the antidepressant effect of DMT (n = 4). The abbreviations are explained in the footer.
| Authors | Year | Type of Study | Sample Size | Characteristic of Participants | Intervention | Results | Conclusions | QATQS Global Rating |
|---|---|---|---|---|---|---|---|---|
| Palhano-Fontes et al. [30] | 2019 | RCT | 29 | Subjects with treatment-resistant major depressive disorder (MDD) | Patients received a single dose of either ayahuasca or placebo. Effects in depression severity were assessed with the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Hamilton Depression Rating scale at baseline, and at 1 (D1), 2 (D2), and 7 (D7) days after dosing |
Significant antidepressant effects of ayahuasca when compared with placebo at all-time points. MADRS scores were significantly lower in the ayahuasca group compared with placebo at D1 and D2 and at D7. Response rates were high for both groups at D1 and D2, and significantly higher in the ayahuasca group at D7 (64% vs. 27%). Remission rate showed a trend toward significance at D7 (36% vs. 7%) | This study brings new evidence supporting the safety and therapeutic value of ayahuasca, dosed within an appropriate setting, to help treat depression | 1 |
| Osório et al. [31] | 2015 | Non-RCT (open-label trial) | 6 | Subjects with current depressive episode | Patients received 120–200 mL of ayahuasca. Effects in depression severity were assessed with measured on the Hamilton Rating Scale for Depression (HAM-D), the Montgomery-Åsberg Depression Rating Scale (MADRS), and the Anxious-Depression subscale of the Brief Psychiatric Rating Scale (BPRS) | Statistically significant reductions of up to 82% in depressive scores were observed between baseline and 1, 7, and 21 days after ayahuasca administration | These results suggest that ayahuasca has fast-acting anxiolytic and antidepressant effects in patients with a depressive disorder | 3 |
| Sanches et al. [32] | 2016 | Non-RCT (open-label trial) | 17 | Subjects with recurrent depression episode | Patients receive ayahuasca (2.2 mL/kg) and were evaluated with the Hamilton Rating Scale for Depression, the Montgomery-Åsberg Depression Rating Scale, the Brief Psychiatric Rating Scale, the Young Mania Rating Scale, and the Clinician Administered Dissociative States Scale during acute ayahuasca effects and 1, 7, 14, and 21 days after drug intake | Increased psychoactivity (Clinician Administered Dissociative States Scale) and significant score decreases in depression-related scales (Hamilton Rating Scale for Depression, Montgomery-Åsberg Depression Rating Scale, Brief Psychiatric Rating Scale) from 80 min to day 21 | Results suggest that ayahuasca may have fast-acting and sustained antidepressive properties. These results should be replicated in randomized, double-blind, placebo-controlled trial. | 3 |
| Zeifman et al. [33] | 2020 | Non-RCT (open-label trial) | 17 | Subjects with major depressive disorder (MDD) | Patient received single dose of ayahuasca and were evaulated with The Montgomery-Åsberg Depression Rating Scale | Among individuals with suicidality at baseline (n = 15), there were significant acute (i.e., 40, 80, 140, and 180 min after administration) and post-acute (1, 7, 14, and 21 days after administration) decreases in suicidality following administration of ayahuasca | Ayahuasca could possibly lead to rapid and sustained reductions in suicidality among individuals with MDD Randomized, double-blind studies with larger sample sizes are needed to confirm this early finding | 3 |
QATQS—Quality Assessment Tool for Quantitative Studies, RCT—randomized controlled trial, Non-RCT—non- randomized controlled trial, MDD—major depressive disorder, BPRS—Brief Psychiatric Rating Scale, MADRS—Montgomery-Åsberg Depression Rating Scale, HAM-D—Hamilton Rating Scale for Depression.