Age and Cannabis Co-Use Are Associated with Differences in Experience and Perceived Benefits of Psilocybin: A Retrospective Study.

As psychedelic use increases, understanding how demographic and behavioral factors influence the effects of psychedelics is essential for both research and public health. This cross-sectional retrospective study examined 365 people who currently use psilocybin, analyzing differences in acute experiences, psychological outcomes, and substance co-use patterns. Participants were categorized into young (18-25), middle-aged (26-54), and older (55-77) adults. Results showed that younger participants reported significantly more adverse experiences while older adults had milder effects. Despite differences in adverse experiences, age did not significantly impact mystical experiences, psychological insight, or psychological outcomes. Polysubstance use patterns also varied by age, as younger adults were more likely to co-use nicotine with psilocybin. Cannabis co-use specifically was associated with greater perceived improvements in quality of life, anxiety, depression, and alcohol abuse, suggesting potential synergies between psilocybin and THC. These findings emphasize that age and cannabis co-use may modulate aspects of psilocybin's acute effects and therapeutic outcomes. Given the increasing legalization and accessibility of psychedelics, future research should further investigate mechanisms underlying individual differences and assess the impact of polysubstance use with psychedelics.