Table 4.

Summary of studies using psilocybin for tobacco use disorder

Substance	Author(s)	Year	Study characteristics	Dose	Main findings
a. Psilocybin	Johnson et al. [51]	2014	Open-label pilot study	Moderate: 20 mg/70 kg	80% self-reported quitting smoking (biologically verified smoking abstinence) throughout the weeks of active treatment
			Fifteen nicotine-dependent smokers with previous unsuccessful quit attempts, still desiring to quit	High: 30 mg/70 kg	80% were abstinent at 6-month follow-up
			15-week smoking cessation CBT with three psilocybin sessions (at 5, 7, and 13 optional weeks)		Significant reductions in self-reported daily smoking from first psilocybin session to 6-month follow-up
					Significantly decreased craving
					At 12-month follow-up, 10/12 (67%) returning participants were smoking abstinent (Johnson et al. 2017)
					At long-term follow-up (average 30-months), 9/12 (60%) were smoking abstinent (Johnson et al. 2017)
	Garcia-Romeu et al. [53]	2015	Open-label pilot study	Session 1 (moderate): 20 mg/70 kg	At 6-month follow-up 80% were abstinent
			Fifteen smokers with previous unsuccessful quit attempts, still desiring to quit	Session 2 (high): 30 mg/70 kg	The abstinent individuals scored significantly higher on a measure of psilocybin-occasioned mystical experience relative to participants still smoking at 6 months
			15-week smoking cessation treatment intervention (CBT and mindfulness training) with two psilocybin session at week 5 and 7 and an optional high third dose at week 13		60% met criteria for “complete” mystical experience which was significantly correlated with smoking cessation outcome
	Johnson et al. [52]	2017	Retrospective cross-sectional anonymous online survey	Psilocybin	38% reported continuous smoking cessation after psychedelic use (Quit group)
			358 individuals who reported having quit or reduced smoking after ingesting a psychedelic in a non-laboratory setting	LSD	74.5% of the “Quit group” reported >2 years of abstinence
				Mescaline	28% reported a persisting reduction in smoking (Reduce group)
				DMT/Ayahuasca	62% of the “Reduce group” reported >2 years reduction in smoking
				Dose N/A	34% reported temporary reduction in their smoking before returning to baseline smoking level (Relapse group)
					Participants across all groups reported less severe affective withdrawal symptoms (e.g., depression, craving) after psychedelic use compared with previous quit attempts
					Participants in the “Relapse group” rated the reference psychedelic experience as significantly less personally meaningful than those in the “Quit group”

CBT, cognitive behavioural therapy; DMT, N, N-dimethyltryptamine; LSD, lysergic acid diethylamide.