Research Square
August 23, 2024
Mathias E. Jensen, Dea Siggaard Stenbæk, Catharina Messell et al.
1 citation
A single 25 mg dose of psilocybin, given with preparation and integration sessions, reduced alcohol consumption in ten adults with severe alcohol use disorder. Heavy drinking days dropped by 37.5 percentage points over 12 weeks, and drinks per day decreased by 3.4 units. Participants also reported rapid and lasting reductions in craving and increased self-efficacy. Blood levels of the active metabolite psilocin varied widely between individuals, peaking from 14 to 59 µg per liter. The open-label study, which lacked a placebo group, suggests that even a single psilocybin session may be safe and effective, but larger randomized controlled trials are needed.
Nature Communications
June 24, 2026
Drummond E-Wen Mcculloch, Anders S. Olsen, Brice Ozenne et al.
A prominent theory holds that psychedelics increase brain entropy, but past studies have used many different entropy measures. This work analyzed 121 fMRI scans from 28 healthy adults before and after psilocybin, testing 14 entropy metrics with two brain-parcellation methods and seven denoising pipelines. Five metrics—including Shannon entropy of spatial eigendistribution, path-length, instantaneous correlations, brain-state switching, and sample entropy at short time-scales—consistently showed positive associations with psychedelic effects. However, eight metrics showed no significant effects, and Lempel-Ziv complexity gave inconsistent positive results. The entropy measures correlated poorly with each other, indicating that brain entropy is not a single, unified phenomenon.
Research Square
October 10, 2025
Gitte M. Knudsen, Annette Johansen, Pontus Plavén‐sigray et al.
A single dose of psilocybin increases synaptic density in the frontal cortex and hippocampus of healthy individuals, but the magnitude of this effect depends on the environment in which the experience occurs. Participants who took psilocybin in a therapeutic-like room reported more intense mystical-type experiences, longer-lasting psychological benefits, and showed greater increases in synaptic density compared to those dosed inside an MRI scanner. These findings indicate that psilocybin's neuroplastic effects are modulated by environmental context, with implications for psychedelic-assisted therapies.