A systematic review and meta-analysis of nine studies found that people who consume psychedelics have higher levels of brain-derived neurotrophic factor (BDNF) than healthy controls, with a pooled standardized mean difference of 0.26. This suggests psychedelics may influence neuroplasticity by altering BDNF, potentially enhancing synaptic plasticity and neuron growth. However, due to limited data, the conclusions remain uncertain, and more research with larger samples is needed.
Psilocybin, a classic hallucinogen, produces a large and clinically observable reduction in depressive symptoms when added to supportive therapy, compared to baseline measurements and to placebo. The effect remains significant across various time intervals after administration. This systematic review and meta-analysis substantiates that psilocybin is superior to psychotherapy alone for treating depression, warranting further studies with larger samples and longer follow-up.