Can the use of psychedelic drugs induce lasting changes in metaphysical beliefs? While it is popularly believed that they can, this question has never been formally tested.
Here we exploited a large sample derived from prospective online surveying to determine whether and how beliefs concerning the nature of reality, consciousness, and free-will, change after psychedelic use.
Results: revealed statistically-significant shifts away from ‘physicalist’ or ‘materialist’ views, and towards panpsychism and fatalism, post use. With the exception of fatalism, these changes endured for at least 6 months, and were positively correlated with the extent of past psychedelic-use and improved mental-health outcomes. Path modeling suggested that the belief-shifts were moderated by impressionability at baseline and mediated by perceived emotional synchrony with others during the psychedelic experience.
The observed belief-shifts post-psychedelic-use were consolidated by data from an independent controlled clinical trial.
Together, these findings imply that psychedelic-use may causally influence metaphysical beliefs—shifting them away from ‘hard materialism’. We discuss whether these apparent effects are contextually independent.
…We compared NPB scores before attending a ceremony involving psychedelic use (baseline) with NPB scores 4 weeks and 6 months after the ceremony. Pooling scores for the NPB factor, analyses revealed a statistically-significant shift away from physicalism at 4 weeks compared with baseline (t(121) = 3.66, p = 0.001, d = 0.33, 95% confidence interval [0.12, 0.39]). These changes were sustained 6 months after the ceremony (t(121) = 5.07, p < 0.0001, d = 0.46, 95% CI [0.22, 0.50]) (Figure 1a). Larger effect-sizes were found for respondents who were embarking on their first psychedelic experience (the so-called ‘psychedelic naïve’), with statistically-significant changes found at 4 weeks (t(52) = 3.85, p = 0.001, d = 0.53, 95% CI [0.21, 0.66]) and 6 months (t(52) = 5.32, p < 0.0001, d = 0.73, 95% CI [0.36, 0.80]) (Supplementary Figure 1a). Analyses of each individual item for the NPB factor revealed increases in notions of transcendentalism, mind-body dualism, and panpsychism—among others, with some changes remaining statistically-significant for 6 months (see Figure 1b-left and Supplementary Figure 1b for findings for ‘naïve’ respondents). Additionally, a statistically-significant positive correlation was found between previous psychedelic use and shifts away from the hard-materialism pole of the hard-materialism vs. hard-dualism spectrum (Figure 1b-right) at baseline (r = 0.223, p < 0.0001).
…Validation with data from a controlled clinical trial: To test the validity and replicability of our findings, we included items corresponding to the NPB in a double-blind randomized controlled trial comparing a group (n = 30) receiving psilocybin therapy with another undergoing a 6-week course of escitalopram (n = 29) (See “Methods” for details of trial design).
Results replicated well across the independent studies. That is, a statistically-significant drug versus time (before treatment and 6 weeks after) interaction was observed (F(56) = 3.13, p = 0.041, one-tailed). More specifically, post-hoc tests reveal that shifts away from hard materialism were evident in the psilocybin group only (Z = 2.28, p = 0.02, d = 0.45). The escitalopram group showed no changes in NPB (Z = 0.24, p = 0.33, d = 0.2). (Figure 5a). Importantly, consistent with the above-reported findings of a relationship between belief shifts and positive mental health outcomes, statistically-significantly greater shifts away from hard materialistic beliefs (the NPB factor) were found for those patients who showed a clinically meaningful response to psilocybin only (response is defined as at least 50% reduction in depression scores from baseline to week 6), versus those who showed a response to escitalopram (Z = 1.74, p = 0.041, g = 0.56, 90% CI [−0.17, 1.26]) (Figure 5b). Finally, we found that the belief-shifts in the psilocybin condition were largely correlated with positive endorsement of an unifying spiritual principle (measured at the same timepoints as metaphysical beliefs; see “Supplementary Methods” for the items used), indicating that changes in metaphysical beliefs are related to changes in spiritual beliefs, and are specific to the action of psychedelics versus a conventional antidepressant drug (Figure 5c).
