Study finds psilocybin lacks lasting behavioral effects in mice

A multi-laboratory investigation has determined that a single dose of psilocybin does not produce reproducible, long-term behavioral changes in mice. The findings, published Nov. 2 in the journal Nature Neuroscience, challenge common assumptions regarding the enduring benefits of the compound in animal models.

The research was conducted by the Psychedelic Bay Area Animal Neuroscience Consortium, a group comprising five independent labs from UC Berkeley, UCSF, and Stanford University. To ensure consistency across the study, the researchers utilized a standardized methodology involving C57BL/6J mice aged 10 to 14 weeks, administering a 2 mg/kg dose via injection.

While the study confirmed robust acute effects, such as a head-twitch response and reduced fear expression approximately 10 minutes after administration, the results showed no replicable reductions in anxiety or depression-like behaviors 24 hours later. The data also indicated no significant improvements in social learning or fear extinction.

Odilia Lu, a doctoral student at UC Berkeley and co-first author of the paper, noted that the persistent effects of psilocybin across the observed behaviors were modest at best. She emphasized that the study highlights the necessity of multi-lab collaborations to accurately estimate effect sizes and mitigate the risk of publication bias in psychedelic research.

The research team stated that these findings underscore the urgency of conducting large-scale replication studies to better understand the compound's impact. The study remains distinct from other recent efforts that have sought to separate the hallucinogenic properties of psilocybin from its potential brain-rewiring effects.