Psychopharmacology
March 1, 2004
Felix Hasler, Ulrike Grimberg, Marco A. Benz et al.
458 citations
Psilocybin, a serotonin 5-HT(2A) receptor agonist, dose-dependently altered consciousness, attention, and mood in eight healthy subjects. At medium and high doses (215 and 315 micrograms per kilogram body weight), performance on an attention test dropped by 50%, and participants reported increased emotional excitability, dreaminess, and general inactivation. Only one person experienced transient anxiety at the highest dose. Blood pressure rose modestly after the high dose, and levels of the hormones TSH, ACTH, cortisol, and prolactin increased during peak effects, with prolactin rising after both medium and high doses. No changes occurred in heart rhythm or body temperature. The authors conclude psilocybin affects core dimensions of consciousness and physiology in a dose-dependent manner and found no evidence of harm to physical health.
Neuropsychopharmacology
January 1, 2003
Daniel Umbricht, Franz X. Vollenweider, Liselotte Schmid et al.
192 citations
The NMDA receptor antagonist ketamine disrupts auditory mismatch negativity (MMN) and performance on an AX-type continuous performance test (AX-CPT), similar to deficits seen in schizophrenia. This placebo-controlled study tested the 5-HT(2A) receptor agonist psilocybin on the same measures in 18 healthy volunteers. Psilocybin caused significant performance deficits on the AX-CPT but did not significantly reduce MMN generation. These results suggest that deficient MMN generation in schizophrenia may specifically reflect NMDA receptor dysfunction, while impairments in AX-CPT performance during both psilocybin and ketamine administration may stem from shared disruption of glutamatergic neurotransmission. Comparable deficits in schizophrenia may arise from independent dysfunctions of 5-HT(2A) and NMDA receptor-related neurotransmission.
Sci Rep
October 24, 2019
Lukasz Smigielski, Michael Kometer, Milan Scheidegger et al.
174 citations
In a mindfulness group retreat setting, the acute and sustained effects of psilocybin were characterized and predicted. The study examined how individuals responded to the psychedelic during and after the retreat, identifying factors that influenced the strength and duration of the experience. Results showed that certain psychological and contextual variables predicted more profound acute responses, which in turn were associated with greater long-term improvements in well-being. The findings suggest that psilocybin's effects in a group mindfulness context are shaped by individual differences and the retreat environment, offering insights into optimizing therapeutic use.