Of all the claims for the power of ayahuasca to heal sicknesses of various kinds, from cancer to asthma, the most popular current claim is that ayahuasca can — in some sense — cure addiction. I have nothing but respect for the proponents of this claim, especially people like Gabor Maté and Jacques Mabit, who have committed their professional lives to establishing the effectiveness of this treatment. There are certainly anecdotes, claims, and uncontrolled self-report studies that can at best be called preliminary. A recent article in Current Drug Abuse Reviews, for example, reports “statistically significant improvements in several factors related to problematic substance use” after a four-day ayahuasca retreat in a rural First Nations community. But I have seen no substantial scientific evidence that ayahuasca can in fact successfully treat addictions. Here is why I am cautious about such claims.

First, I am not even sure what such a claim would mean. Addictions differ from each other. Heroin addiction is very different from methamphetamine addiction, and both, in turn, are very different from nicotine addiction, not least because heroin and methamphetamine are illegal and nicotine is not. And all three are different in turn from such behavioural addictions as those to gambling or chronic overeating. And then there are also repetitive behaviours that are problematic but not necessarily addictions. Is a bulimic addicted to vomiting? And which of these is ayahuasca claimed to treat? Of course, one could argue that ayahuasca somehow cures everything, but I would be even more sceptical of such a claim.

Further, I am not sure how such a claim can be made in the absence of reliable data on recidivism rates as a function of time. Remember that many programs claim to treat addiction — charismatic religious groups, family interventions, commercial detoxification centers, methadone clinics, and twelve-step programs. I am aware of no data showing that ayahuasca treatments do any better than such programs, which apparently do not do well at all. And long-term controlled follow-up studies are the only way to tell.

One reason that long-term follow-up is needed is that many new or novel interventions often have high initial success. The patient feels specially selected, the proponents are enthusiastic and optimistic, there is a lot of interviewing and record-keeping and heightened interest in the well-being of the patient. But then, often, two things happen. The patients who have shown initial improvement revert to their earlier status; and, over time, as the novelty and interest wear off, the treatment becomes less successful.

Most important, I think, such claims of cure, or even just amelioration, often ignore the significant economic, social, and cultural components of addiction. Junkies and gamblers are both parts of social networks that reinforce their behaviour. Shooting up and playing the horses are both cultural activities — indeed, for many participants, they amount to careers, with an in-group, language, customs, legends, and trajectory. Most addicts can stop addictive behaviour when isolated from this reference group, in prison, say, or in a remote rehab center; in many cases, the behavior quickly begins again when the addict, often with no place else to go, returns to the addict culture.

Finally, addictions may, like many diseases, be self-limiting. As with crime, addicts may simply age out. As William S. Burroughs famously said, there are no old junkies; the ones who do not die eventually just stop. As with other claims to healing, the self-limiting nature of many addictions is an uncontrolled variable which raises questions about the role of the intervention in stopping the behaviour.

Perhaps I will be proven wrong.