A phase IIa trial was randomized and placebo-controlled, testing the short-acting psychedelic dimethyltryptamine (DMT, SPL026) in combination with psychological support in 34 adult patients with moderate to severe major depressive disorder (MDD).[1] Patients discontinued antidepressants prior to the single intravenous dose.[1] After one week of treatment, DMT patients had an average of 10.8 points lower Montgomery-Åsberg Depression Rating Scale (MADRS) scores compared to placebo.[1] After two weeks, the score was another 7.4 points lower.[1] The results showed a statistically significant and clinically relevant reduction in depressive symptoms.[1] A single dose with supportive therapy had significant antidepressant effects lasting up to three months.[1] A second phase of the study was opened to compare the effect of one or two doses and to observe the durability of the effect.[1]