Background: Despite tetrahydrocannabinol (THC)'s reputation for creating dramatic effects at high doses, empirical work rarely addresses cannabis's impact on subjective responses common to the tryptamine psychedelics. We focused on these effects because they have preceded and covaried with the therapeutic impact of psilocybin in previous work.
Aims: The current study examined if self-reported responses to cannabis products might parallel those found in clinical trials of psilocybin administration. We also investigated if measures of demographics and cannabis use might correlate with these responses.
Methods: Participants reported the subjective effect of their highest THC experience using 27 items that assess oceanic boundlessness, a correlate of mystical experiences. They also answered infrequency items and questions on demographics and cannabis consumption.
Results: In an effort to address concerns about replication, we divided respondents who passed infrequency items into two random samples. Self-reported "breakthrough" experiences were significantly greater than zero but significantly lower than those reported in randomized clinical trials of psilocybin (17-19% vs. 59%). Total scores covaried with perceived dosages of THC, but only in one sample. Heavier users of cannabis reported lower scores.
Conclusions: Self-report data suggest that high doses of cannabis can create subjective effects comparable to those identified in trials of psilocybin that precede relief from cancer-related distress, treatment-resistant depression, alcohol problems, and cigarette dependence. Given the disparate mechanisms of action, comparing THC-induced to psilocybin-induced effects might improve our understanding of the mechanisms underlying subjective experiences. This work might also support the development of a cannabis-assisted psychotherapy comparable to psilocybin-assisted psychotherapy.
Keywords: Tetrahydrocannabinol; cancer; cigarettes; depression; mystical experiences; oceanic boundlessness; psychedelic-assisted psychotherapy.