Psilocybin, a serotonergic hallucinogen, strongly decreased prestimulus parieto-occipital alpha power and reduced N170 visual-evoked potentials in healthy humans, effects linked to visual perceptual alterations including hallucinations. These changes were blocked by pretreatment with the 5-HT2A receptor antagonist ketanserin, indicating that activation of 5-HT2A receptors by psilocybin modulates visual processing by overwhelming stimulus-driven cortical excitation with spontaneous neuronal excitation via alpha oscillations. The reduction in N170 potentials may be a key mechanism underlying 5-HT2A receptor-mediated visual hallucinations, relevant not only to psilocybin-induced states but also to acute hallucinatory states in psychiatric disorders such as schizophrenia and Parkinson's disease.
A single, moderate dose of psilocybin (0.215 mg/kg body weight) significantly reduced depressive symptoms compared to placebo in adults with major depressive disorder. Over two weeks, depression severity scores dropped by 13.0 points on the MADRS and 13.2 points on the BDI in the psilocybin group, with improvements significantly larger than in the placebo group. 54% of participants receiving psilocybin met remission criteria. No serious adverse events occurred. The findings suggest psilocybin offers rapid antidepressant effects, though larger, longer-term trials are needed.
A correction was issued for a figure in a clinical trial on psilocybin-assisted therapy for major depressive disorder. The colors representing the Psilocybin and Placebo conditions were swapped in Fig. 2; the correction aligns them with the caption and other figures. The error does not affect the results. The trial found that a single, moderate dose of psilocybin significantly reduces depressive symptoms compared to placebo for at least two weeks, with no serious adverse events. Larger, multi-centric trials with longer follow-up are needed to optimize this treatment.