A systematic review and meta-analysis assessed the risk of psychedelic-induced psychosis in people with schizophrenia. Among population studies, the incidence was 0.002%; in uncontrolled trials, 0.2%; and in randomized controlled trials, 0.6%. In uncontrolled trials that included individuals with schizophrenia, 3.8% developed long-lasting psychotic symptoms. Of those who experienced psychedelic-induced psychosis, 13.1% later developed schizophrenia. The evidence suggests schizophrenia might not be an absolute exclusion for clinical trials on psychedelics for treatment-resistant depression and negative symptoms, but low study quality and limited data warrant a conservative approach until more research is done.
A living systematic review with meta-analysis examined the efficacy, safety, and all-cause discontinuation of serotonergic psychedelics and MDMA for treating mental disorders. The review found that these substances show promise in reducing symptoms of conditions such as depression, anxiety, and post-traumatic stress disorder, with some evidence supporting their therapeutic potential. However, the authors note that the overall quality of evidence is limited by small sample sizes, short follow-up periods, and methodological concerns. Safety profiles varied, with most adverse events being mild to moderate, though serious adverse events were reported in some studies. The review emphasizes the need for larger, more rigorous trials to confirm these findings.
A systematic review and meta-analysis of 26 randomized clinical trials with 1,166 patients experiencing a major depressive episode found that intravenous ketamine infusions significantly reduce suicidal and depressive symptoms in the acute phase. A single ketamine infusion lowered suicidal symptoms at 24 hours and at 1 month, and repeated infusions produced similar reductions. Depressive symptoms decreased significantly from 4 hours through 1 week after a single infusion and after repeated infusions. Serious adverse events were unrelated to the interventions, and other side effects were transient. Longer-term outcomes remain unclear.