Efficacy of psychedelic treatments on depressive symptoms: A meta-analysis.

Psychedelic drugs have shown an efficacy in some psychiatric disorders and have an original mechanism of action with a 5-HT agonism. The aim of this meta-analysis was to assess by a quantitative analysis the putative efficacy of psychedelic drugs on depressive symptoms and to investigate the kinetic of this efficacy. We searched the MEDLINE and PsycINFO databases through April 2019, without limits on year of publication. Means and standard deviations were extracted to calculate standardized mean differences (SMD). Scores of depressive symptoms were compared with baseline scores at days 7, 14, and 21; weeks 4-5 and 6-8; and months 3 and 6. Eight studies were included in this meta-analysis. A significant decrease of depressive symptoms was found from day 1 ( = 5 studies; SMD = -1.4, 95% confidence interval (CI): -2.33 to -0.48, = 0.003) to 6 months ( = 4 studies; SMD = -1.07, 95% CI: -1.44 to -0.7, This meta-analysis shows that psychedelic treatments were safe and could contribute to a rapid improvement of depressive symptoms.