Does cannabis availability help prevent opioid overdoses?

There’s been lots of chatter about the cannabis-opioid substitution question.

Newsweek headlines, “Can Legal Marijuana Solve the Opioid Crisis?”  while Dr. Jeff Sessions opines that cannabis is “only slightly less awful” than heroin.

People whose background is medical research tend to distrust anything that’s not a randomized controlled trial. They point to the positive correlation between cannabis use and opioid use at the individual level, and the fact that opioid deaths continue to rise even where cannabis is most freely available. Their position is, “We don’t know anything about this. Let’s due the clinical studies before taking action.”

But “not taking action” now means continuing to criminalize even the possession of cannabis. If cannabis substitutes for opioids, those laws cost lives: lives that can’t be regained ten years from now, after the clinical-trial results are in.

Moreover, the relevant clinical trials can’t actually be done in the U.S. The DEA-imposed University of Mississippi monopoly on the production of cannabis for research means that the cannabis available for research bears little resemblance to the products available in California dispensaries or Washington or Colorado cannabis stores. It’s lower in potency; it’s all flower rather than extract; it doesn’t embrace the wide variety of strains – each with its own chemical composition – now available commercially. It’s entirely possible that “Mississippi mud” doesn’t effectively substitute for opioids, but that the average dispensary product does, or that the average dispensary product doesn’t but some do. That’s one reason clinical trials with cannabis are so hard: cannabis isn’t one thing, it’s thousands of different mixtures of hundreds of different active chemicals.

Fortunately, there are other valid means of inquiry. You can look at the pattern of opioid prescriptions, treatment admissions, and overdose deaths before and after the passage of “medical marijuana” or full-legalization laws, and also study what happens as the number of outlets. the number of registered users, or the volume of product sold grows, and also what happens when a state reins in a previously wide-open “medical marijuana” system.

To a clinical researcher, these are all merely “ecological studies,” just one step up from chiromancy. But in fact econometricians have developed enormously sophisticated techniques of time-series analysis that allow solid causal inferences to be drawn from non-experimental data.

Rosalie Pacula and her team at the RAND Drug Policy Research Center have been doing such studies. Here’s their summary of the findings, which are consistent with studies done by other researchers:

* The relationship between medical marijuana laws and reductions in opioid overdoses is complex.

* Medical marijuana laws vary in their effect on reducing opioid overdoses.

*States with medical marijuana dispensaries experienced reductions in opioid-related overdoses.

* As states have become more stringent in regulating dispensaries, the protective value of medical marijuana laws generally has fallen.

* These findings suggest that broader access to medical marijuana facilitates substitution of marijuana for powerful and addictive opioids.

Is that a definitive finding? No.

Does it specify a mechanism? No.

Perhaps some patients find they can use cannabis instead of opioids for pain relief (which, it’s worth remembering, means not just reducing pain perception but making the experience of pain less stressful). Perhaps others find that they can use cannabis to get the same level of pain relief with lower doses of opioids. Perhaps some non-medical users use cannabis, when it’s available, instead of opioids. In still other cases cannabis might substitute not for the opioids themselves, but for the alcohol or benzodiazepines that, used in combination with the opioids, enhance the experience but also multiply the risk of fatal overdose by potentiating opioid respiratory suppression. Or cannabis might make withdrawal from opioids more bearable. Any or all of those effects could be at work.

Nonetheless, with these results in hand, if you asked me to bet on whether easing access to cannabis in a given state was likely to reduce the rate of increase in opioid overdoses in that state, I’d want very long odds to bet on “No.” Since, if the substitution effect is real, waiting costs lives, I think that’s a strong argument for going ahead with liberalizing cannabis access, whether under the guise of “medical marijuana” or (as I’d now prefer for other reasons) with frank legalization for adult use.

Of course that potential benefit needs to be weighed against the costs of liberalization in the form of increased prevalence of Cannabis Use Disorder. (Those costs could be minimized with well-designed legalization, but that’s not the legalization we’re actually getting.)

So it’s not irrational to remain a cannabis-policy hawk in the face of the opioid substitution findings. But it’s no longer reasonable to say, “We don’t know anything about whether cannabis substitutes for opioids.” We know enough to have a strong hunch.

I should add that these findings came as a complete surprise to me. Naturally, I can invent explanations for the fact of substitution now that there’s evidence for it, but I didn’t predict it. I did predict substitution for alcohol – that seemed to me among the strongest arguments for cannabis legalization, even back when I was mostly against it – but that prediction turned out to be wrong. The study that convinced me that there wasn’t substitution for alcohol – part of Rosanna Smart’s thesis work – also provided the first convincing evidence I’d seen of opioid substitution. That wasn’t something Smart had been looking for; it just popped out of the data.

The world is a complicated place. We should be prepared for surprises, and willing to learn from the findings of more than one research tradition.

Author: Mark Kleiman

Professor of Public Policy at the NYU Marron Institute for Urban Management and editor of the Journal of Drug Policy Analysis. Teaches about the methods of policy analysis about drug abuse control and crime control policy, working out the implications of two principles: that swift and certain sanctions don't have to be severe to be effective, and that well-designed threats usually don't have to be carried out. Books: Drugs and Drug Policy: What Everyone Needs to Know (with Jonathan Caulkins and Angela Hawken) When Brute Force Fails: How to Have Less Crime and Less Punishment (Princeton, 2009; named one of the "books of the year" by The Economist Against Excess: Drug Policy for Results (Basic, 1993) Marijuana: Costs of Abuse, Costs of Control (Greenwood, 1989) UCLA Homepage Curriculum Vitae Contact:

19 thoughts on “Does cannabis availability help prevent opioid overdoses?”

  1. Well, in the late 70s Amsterdam had a heroin epidemic on its hands, and the legalization of pot had a demonstrable effect on the reduction of heroin use. It's not an apt metaphor for the situation in the U.S., but it's instructive. After a spike in marijuana use, the level declined to maybe number 6 or 8 in the E.U. High (no pun intended), but less than American rates. But the level of heroin use plummeted to one of the lowest on the Continent.

    Perhaps the most significant effect of legalization and regulation was that for many years thereafter Holland had the lowest teenage response rate to the question: "can you get harder drugs through your pot dealer?" The woman behind the counter at the coffee shop in Maastricht absolutely will not sell you meth or coke or heroin. Nor in Denver.

    Whereas I remember (with a bit of nostalgic fondness) my pot dealers in college mentioning that they had some coke or some hash oil or some peyote buttons or some Thai stick or some opium or some 4-way blotter acid…….

    ….so heavily regulated O-T-C marijuana may very well have an effect on the availability of other shit, at the pot-dealer level. It did in Holland. And, from my subjective experience as a college druggie, I couldn't get that heavy shit at the local liquor store.

    1. This line in the article suggests that your anti-gateway hypothesis might have some validity: "As states have become more stringent in regulating dispensaries, the protective value of medical marijuana laws generally has fallen." The more stringent the regulation, the more plausible that at least some borderline patients will go to or stay in the illegal market.

      A big question for me is how much is known about who overdoses. Even if the market as a whole doesn't show strong substitution effects, could it be that the minority most vulnerable to OD are getting something they need at dispensaries? (Possibly not just the cannabis but also some interaction that differs from their interaction with illicit suppliers)

      1. Well, then there's the potency issue. I had a few Match dates with a woman whose son had lost both legs in a grenade attack in Iraq. One evening she had me by her place for a few games of chess, and I mentioned that it smelled like some good shit she was smoking. She yelled down the cellar stairs and a few moments later a big strong young man knuckle hopped to the top of the stairs and across the living room. He had a box hanging from his neck. Once his hands were free, he opened it up and pulled out the most elaborate suite of paraphernalia, had to teach me how to use this gadget or that, and I woke up on the couch at 3AM. No recollection of the chess games or movie we clicked up on Netflix. The modern "putty" and "gel" and whatnot is ridiculously potent, and those atomizing/vaporizing delivery mechanisms really concentrate it. So, I mean, it could absolutely replace Ambien, for example. And here was a man with nothing left of his body below the waist, who was clearly traumatized and unhappy, but using it as his go-to medication. Obviously anecdotal evidence isn't truly evidence, but the shit is opioid strong these days.

    2. The Netherlands undertook a number of other drug-enforcement reforms beyond tolerating cannabis though, did they not? IIRC that was part of a broader effort to break recruitment into the black market, including providing opioids to users who would register themselves as addicts. And spending real money on outreach backed with social services.

      1. I'm sure you're correct. My research was commissioned by a travel magazine for an article called Hookers & Hash For The Elderly Traveler, so I became reasonably well versed on the marijuana and prostitution history, but mostly for introductory context — the rest of the article was a how-to guide, with no examination of narcotics or the criminal justice system or addiction services, etc.

        1. > My research was commissioned by a travel magazine for an article called Hookers & Hash For The Elderly Traveler… a how-to guide…

          Sounds like a memorable assignment.

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