Johnson et al. 2017 – Psilocybin for smoking cessation


Johnson et al. 2017 is a follow-up to Johnson et al. 2014, a pilot study looking at high-dose psilocybin therapy for smoking cessation.

The 15 participants of the pilot study received two or three psilocybin trips, along with four preparatory cognitive-behavioral therapy sessions. Johnson and friends then followed up with participants for about two years after their trips, tracking their smoking behavior.

So, what'd they find?

All 15 participants completed a 12-month follow-up. Twelve (80%) returned for a long-term follow-up (mean 30 months post-target quit date (TQD); range = 16–57 months) and provided data regarding current smoking and past treatment experience.

At 12-month follow-up, 10 participants (67%) were biologically confirmed as smoking abstinent, with 8 of these participants reporting continuous abstinence since their TQD. At long-term follow-up, nine participants (60%) were biologically confirmed as smoking abstinent, with 7 of these participants reporting continuous abstinence since their TQD.

67% abstinence a year out is pretty impressive, given that these were very heavy smokers – on average 19 cigarettes a day, 31 years smoking, 6 previous quit attempts.

Johnson et al. 2017 tracked biomarker outcomes in addition to self-reported behavior, which is pretty cool:

Participants were judged abstinent if breath CO value was ≤6ppm, urinary cotinine was <200 ng/mL, and if no smoking was reported... for the previous 7 days.

So we can be confident that the participants actually did quit; we're not just relying on self-report.

Johnson et al. 2017 indicates that psilocybin is promising as a smoking cessation intervention, but it's a very small study (n = 15), and open label.

Is there other evidence that psilocybin helps people quit smoking?

Well, the same authors also conducted a survey of naturalistic psilocybin use for smoking cessation.

From the abstract of that survey:

This retrospective cross-sectional anonymous online survey characterized 358 individuals (52 females) who reported having quit or reduced smoking after ingesting a psychedelic in a non-laboratory setting ⩾1 year ago.

On average, participants smoked 14 cigarettes/ day for 8 years, and had five previous quit attempts before their psychedelic experience. Of the 358 participants, 38% reported continuous smoking cessation after psychedelic use (quitters). Among quitters, 74% reported >2 years’ abstinence.

Of the 358 participants, 28% reported a persisting reduction in smoking (reducers), from a mode of 300 cigarettes/month before, to a mode of 1 cigarette/month after the experience. Among reducers, 62% reported >2 years of reduced smoking.

Finally, 34% of the 358 participants (relapsers) reported a temporary smoking reduction before returning to baseline smoking levels, with a mode time range to relapse of 3–6 months. Relapsers rated their psychedelic experience significantly lower in personal meaning and spiritual significance than both other groups.

The average reduction in "reducers" is huge – 300 cigs a month down to 1 per month!

It's probably fair to group the "reducers" and "quitters" into a larger category of "people who's relationship with smoking meaningfully changed", which includes 66% of the people surveyed.

Of course, this is a naturalistic, retrospective survey, so it doesn't tell us very much. Survey participants were selected who "quit or reduced smoking after a psychedelic experience." We have no idea what the base rate is – all the people who tried psilocybin and didn't have success weren't included in this survey.

The most we can say from the survey is that some people found psilocybin useful for quitting smoking.

Summing up, Johnson et al. 2017 provides promising but preliminary evidence that psilocybin can be a useful smoking cessation intervention. As always, more studies (especially bigger ones with control groups) are needed.

The survey by the same authors doesn't add much to this view, as it only surveyed people who reported a positive experience with psilocybin for smoking cessation.