SOURCE : Prohbtd
A 2014 Journal of the American Medical Association (JAMA) study made global headlines when it found that “medical cannabis laws are associated with significantly lower state-level opioid overdose mortality rates” between 1999 and 2010. States with medical cannabis (MMJ) laws had a “24.8% lower mean annual opioid overdose mortality rate” compared to states without such laws. The National Institute on Drug Abuse (NIDA) helped fund the study and included the findings on its Marijuana as Medicine page, but a new NIDA-funded study in Proceedings of the National Academy of Sciences (PNAS) calls those findings into question.
The new research, which confirmed the lower mortality rates through 2010, found that the trend reversed itself after extending the timeline through 2017. The researchers wrote, “States passing a medical cannabis law experienced a 22.7% increase in overdose deaths,” and this inspired headlines like “Researchers debunk claim that medical marijuana is solution to opioid crisis” and “The Misplaced Optimism in Legal Pot.”
NIDA cited the new study saying it “underscores the need for additional research on the effect of MMJ laws on opioid overdose deaths,” but we also need a closer look at the study itself because its findings tell a more complicated tale than the headlines suggest.
The Case for Recreational Cannabis
The researchers’ estimate was not statistically significant and did not list the probability values or the statistical test (unlike the 2014 study) so we don’t know the data’s full story. Keeping these limitations in mind, the study headline could just as easily have read as follows: Recreational cannabis laws are associated with the lowest mortality rate of all and by a significant margin.
“The association between having a recreational cannabis law and opioid overdose mortality was −14.7%,” said the PNAS study. This suggests that recreational cannabis laws, not MMJ laws, are the more accurate correlate with fewer overdose deaths.
The PNAS researchers preempted this conclusion by saying states with recreational laws “form a group that is qualitatively different from the rest of the United States on a number of metrics that may confound estimates.” What is this major difference if not the legalization of recreational cannabis?
Lead researcher Dr. Chelsea Shover tweeted out a few differences like “western geography and Medicaid expansion,” while a press release for the study said the recreational-state differences include being “wealthier and more politically liberal, with greater access to addiction treatment and to naloxone.”
Only four states legalized recreational cannabis before November 2016—conservative Alaska, moderate Colorado and liberal Oregon and Washington—and four of the five states that legalized cannabis in November 2016 had conservative governors in 2017. This makes being “politically liberal” a very strange justification for disregarding a double-digit difference in mortality rates.
By contrast, a new study in Economic Inquiry estimated that recreational cannabis laws may “reduce annual opioid mortality in the range of 20 to 35 percent, with particularly profound effects for synthetic opioids.” One of the authors summarized the findings this way: “Recreational marijuana laws affect a much larger population than medical marijuana laws… [and] we find that opioid mortality rates drop when recreational marijuana becomes widely available via dispensaries.”
A second study in Economic Inquiry reached a similar finding with regard to cannabis access: “County‐level prescription opioid‐related fatalities decline by 11 percent following the opening a dispensary. The estimated dispensary effects are qualitatively similar for opioid‐related admissions to [traditional] treatment facilities.”
The PNAS researchers—who argue that access to traditional treatment matters—rejected the idea that access to cannabis matters because states with CBD-only laws had lower mortality rates than those with MMJ laws.
“If broader access to cannabis writ large, rather than medical cannabis specifically, is the latent factor associated with lower opioid overdose mortality, we would expect to see the most negative association in states with recreational laws and the least negative association (or even positive) association in states with low-THC-only laws,” the study argued.
The first problem with this argument is that “medical cannabis [is only] used by about 2.5% of the U.S. population” (per the researchers) so MMJ laws don’t necessarily denote wider access. Secondly, it ignores the qualitative difference between MMJ states and CBD-only states, which happens to be the most relevant difference of all: the geographics of the worst-hit regions of the opioid epidemic.
The Opioid Epidemic
The original 2014 study featured three states (California, Washington and Oregon) with preexisting MMJ laws and 10 that legalized MMJ between 1999 and 2010. The PNAS study added new states like Arizona, Connecticut, Delaware, Massachusetts, New Hampshire, Illinois, Maryland, New York, Florida, West Virginia, North Dakota, Minnesota, Ohio, Louisiana, Arkansas and Pennsylvania that legalized MMJ between 2011 and 2017.
The opioid epidemic grew significantly during these years with the mortality rate increasing 16 percent per year between 2014 and 2017. Most of the states added to the MMJ list were at the geographic heart of the opioid epidemic in the Midwest and Northeast.
Case in point, four newly added MMJ states (Ohio, New Hampshire, Massachusetts and Connecticut) experienced the highest increases in mortality rates, while West Virginia led the country with the highest rate overall. Moving so many of the worst-hit states onto the MMJ side of the ledger dramatically changed the overdose rate for MMJ states as a whole.
The PNAS study dismissed the lower overdose rates in recreational states because they’re “qualitatively different,” but being one of the worst-hit states when MMJ legalization passed seems more relevant than recreational states like Alaska and Colorado supposedly being “wealthier and more politically liberal” than MMJ states like New York, Illinois and Hawaii.
Even still, the overdose rate for MMJ states only topped non-MMJ states in a single year: 2017. Per the PNAS study, “The direction of the association between medical cannabis laws and opioid overdose mortality was sensitive to the study’s endpoint. For end dates between 2008 and 2012, the association was negative as reported in [the 2014 study]. Subsequently, the association became statistically indistinguishable from zero before turning positive in 2017.”
So, the study disregards the estimates from recreational states yet not from new MMJ states at the heart of an all-time high epidemic and then points to a single year in which the mortality rate in MMJ states entered positive territory. This apparently shows that an association between cannabis access and lower opioid mortality is “spurious.”
For us, it seems spurious to say greater access to non-cannabis treatment justifies disregarding the association between greater cannabis access (via recreational laws) and the lowest mortality rates. Likewise, it’s even more spurious not to disregard MMJ states with little or no MMJ access at all, which brings us to another key qualitative difference.
All MMJ Laws Are Not Created Equal
The Centers for Disease Control and Prevention (CDC) released provisional data this summer that suggests 2018 experienced the first drop in drug overdose deaths since 1990. The CDC estimates a 4.4 percent decrease overall and a dramatic 23.3 percent decrease for hard-hit Ohio, so maybe the overdose rate in MMJ states is about to reverse itself again. Regardless, we must credit harm-reduction strategies for the overdose reduction in Ohio because the MMJ-legal state lacked any dispensary until 2019 and access is limited by high prices and prohibitions on home cultivation and smokable cannabis.
Like the demographics of the opioid epidemic, another key difference the study omitted is the MMJ programs themselves. The researchers defined MMJ states as those that passed laws, and it generally didn’t matter if the programs were extremely limited or not yet operational.
This was the case for many of the newly added states. For example, New Hampshire and Maryland both passed MMJ laws in 2013 but did not open a single dispensary until 2016 and 2017, respectively. Other MMJ states like West Virginia and Ohio did not open a dispensary at all. The PNAS study still counted them as MMJ states, as if a law, not the medical use of cannabis itself, is what might directly reduce overdose deaths.
As summarized in an editorial for The Hill, NORML deputy director Paul Armentano noted, “While the 2014 paper assessed trends exclusively in states with operational medical marijuana access programs, investigators writing in [the PNAS study] did not.”
Then there’s the issue of cannabis-adverse governors. Hard-hit New Jersey legalized MMJ in 2010, but Chris Christie became governor in 2011 and blocked access like it was a bridge to New York City. Since the two-term governor left office last year, the number of MMJ patients has tripled. Maine’s Paul LePage also became governor in 2011 and fought cannabis at every turn. As overdose rates skyrocketed, he reportedly blamed the state’s drug problem on “people of color or people of Hispanic origin” and “guys by the name D-Money, Smoothie, Shifty” from neighboring states who “half the time… impregnate a young, white girl before they leave.” (What an asshole.)
Most of the worst-hit MMJ states were run by conservative governors who were often skeptical about medical cannabis. The overdose epidemic in these states likely played a role in getting MMJ laws passed, but the programs were typically limited in scope and access. These programs were qualitatively different than the ones in states like California, Oregon and Washington where overdose death rates actually decreased. The quality of the program matters.
Norwegian researcher Ole Røgeberg previously sent a letter to the editor of Addiction that framed the MMJ access issue this way: “The latest US state‐level research on medical marijuana laws (MMLs) goes beyond the simple law–overdose correlations criticized in the editorial. Taking policy heterogeneity into account, the reduction in overdose deaths is associated only weakly with MMLs as such, and not with more recently introduced and tightly regulated MMLs. Consistent with a causal link, the association is strongest after dispensaries become operational under MMLs with ‘relatively liberal allowance for dispensaries.’ In these cases, results indicate a 25% reduction in opioid overdoses, along with a 38% decline in treatment admissions for heroin and other opioids.”
Røgeberg’s mention of “in the editorial” refers to a 2018 editorial that heavily criticized the 2014 study on MMJ laws and lower mortality rates. That editorial criticism was co-authored by… wait for it… one of the authors of the 2019 PNAS study.
Qualitative Bias
Whenever a study paints cannabis in a negative light, check out the researchers’ other work. For example, Jeff Hunt of the Centennial Institute produces lots of “cannabis kills” studies that prohibitionist Kevin Sabet (Smart Approaches to Marijuana) loves to quote ad nauseam, but the briefest research suggests the guy who boycotted Beauty and the Beast for pushing a gay agenda is no Albert Einstein.
So, what about the researchers behind the 2019 PNAS study?
We went through every cannabis-related study we could find by any of the four authors, and the most prominent researcher, Dr. Keith Humphreys, is the only one with an extensive list of previously published cannabis research. Across his body of work, the Stanford University professor, VA Health Services Research Center scientist and Addiction journal editor consistently supported evidence of cannabis risk but not evidence of medical applications.
For example, Humphreys co-authored a 2018 study that said cannabis use is associated with an increase in opioid use: “Our findings disconfirm the hypothesis that a population-level negative correlation between medical marijuana use and prescription drug harms occurs because medical marijuana users are less likely to use prescription drugs.”
He doubled down on his gateway drug revival with the tweet, “People who use medical marijuana have higher rates of prescription drug use and misuse (including opioids).”
Notice that he said “disconfirm.” He uses this term because countless other studies suggest cannabis does help reduce pain and opioid use. Examples can be found here, here, here, here, here and in the National Academies of Sciences, Engineering and Medicine’s landmark 440-page cannabis report. His disconfirmation also runs counter to his own PNAS study that found the lowest opioid mortality rates in states with the greatest access to cannabis.
Humphreys described the emerging cannabis market as the alcohol industry “on steroids with very minimal regulation” in The Atlantic article “America’s Invisible Pot Addicts.” He added, “About one in 10 people who smoke [cannabis] say they have a lot of problems…. There are plenty of people who have problems with it, in terms of things like concentration, short-term memory, and motivation. People will say, ‘Oh, that’s just you fuddy-duddy doctors.’ Actually, no. It’s millions of people who use the drug who say that it causes problems.”
Humphreys and Shover collaborated on a 2019 study that said “legalizing states can go beyond reducing possession arrests (which can be accomplished without legalization)” in an apparent nod to decriminalization over legalization. In fact, Humphreys wrote an editorial based on a much-maligned and poorly worded poll by Kevin Sabet’s anti-cannabis organization that he summarized in the tweet “decrim[inalization] more popular than legalization.”
Sabet leads the prohibitionist movement in the U.S., and the idea that Humphreys quotes his work is dodgy yet not unexpected: They both worked as senior advisors at the White House Office of National Drug Control Policy between 2009 and 2010. This is an agency that’s been run by guys like this who reportedly think it’s “morally plausible” to behead American citizens who sell drugs.
Humphreys also collaborated with Dr. Wayne Hall, a.k.a. the Aussie Anslinger. The duo co-authored “It is premature to expand access to medicinal cannabis in hopes of solving the U.S. opioid crisis” criticizing the idea that cannabis can help with the opioid epidemic.
This is the aforementioned criticism addressed by Røgeberg, and it ironically starts, “All human beings are susceptible to confirmatory bias, in that we are inclined to uncritically accept evidence that accords with our pre‐existing beliefs.” Humphreys and Wall directed that criticism toward Røgeberg and others who believe cannabis can help reduce opioid deaths, but they are perhaps guilty of the same bias when uncritically accepting evidence of cannabis harm: i.e., adolescent use can reduce IQ points.
In 2012, a Madeline Meier-led study claimed early cannabis use can lead to IQ reductions. Røgeberg countered that socioeconomic status, not cannabis, accounted for the decline. Hall and Humphreys collaborated again to criticize Røgeberg for his embrace of “weak evidence” in suggesting cannabis 1) reduces opioid overdose deaths but 2) doesn’t reduce IQ points.
Hold your jaw because it’s about to drop: The Hall-Humphreys criticism preceded the 2019 PNAS study that provided the data on which to base such a claim and followed a new Maier-led study where she reversed herself and said adolescent cannabis use does not lower IQs. If that’s not cringeworthy enough, Maier recanted her earlier claim in the journal (Addiction) that Humphreys edits.
Humphreys also criticized the 2014 cannabis-opioid study in a letter to the editor of the publishing journal and co-authored another letter criticizing a study that found “medical cannabis laws are associated with significant reductions in opioid prescribing in the Medicare Part D population… [especially] in states that permit dispensaries.” He wrote a letter in 2019 criticizing the study “Cannabis as a Substitute for Opioids” for overstating the value of pharmacists overseeing New York dispensaries. That same year, he co-authored a study that called it irresponsible and potentially harmful to help opioid addicts recover with medical cannabis (Shover also called it “irresponsible” and “dangerous” here). In turn, researchers criticized his study for having “omitted important facts” in its analysis.
In other instances, Humphreys gives the impression that he thinks most favorable cannabis findings stem from cannabis-funded researchers who embrace weak evidence. In his role with Addiction, he called on researchers to disclose conflicts of interest (e.g., research funding) related to the cannabis industry. The PNAS study similarly noted, “The nonrobustness of the earlier [2014] findings also highlights the challenges of controlling scientific messages in controversial policy areas. Corporate actors (e.g., the medical cannabis industry) with deep pockets have a substantial ability to promote congenial results.”
This is a blatant dig at the 2014 findings (more accurately analyzed here), yet ironically their own study 1) confirmed the lower overdose rates for MMJ states through the original timeframe and 2) produced their own set of questionable headlines that failed to control “scientific messages in controversial policy areas.”
Cannabis Wire reached out to Shover for clarification on these lines, and she said, “That [2014] study’s been cited over 300 times, it’s informed a lot of industry campaigns. Most recently, I’ve seen the Weedmaps billboard and their articles about it.” Like Humphreys, she actively pushes back on such claims (see her tweet below) and admits these types of citations and billboards motivated the 2019 PNAS study.
The researchers are right to question how people use the 2014 findings—and we agree that ecological studies at the population level are not a strong indicator of what’s happening at the individual level—but we failed to find a single instance in which they also challenged negative cannabis claims based on ecological studies, weak evidence or spurious associations.
Humphreys took part in a 2019 cannabis roundtable where he freely cited the risks, but he made no attempt to correct Tell Your Children author Alex Berenson’s many falsehoods. Either that, or Humphreys agrees with Berenson that “marijuana causes psychosis. This is an established medical fact, not open to debate.”
By contrast, roundtable participant Maria McFarland Sánchez-Moreno of the Drug Policy Alliance gave Berenson a beatdown.
“More Research” Cuts Both Ways
To recap, Humphreys spent years criticizing the 2014 findings in editorials, studies and published letters while arguing that MMJ actually increases opioid abuse. This was his position going into the 2019 study, which characterized its findings in a way that confirmed all of his previous claims. In doing so, the study dismissed greater access to MMJ as a possible correlate with lower mortality rates, yet suggested greater access to traditional treatment was why recreational-use states had the lowest mortality rate of all. The study also treated wealth, liberal politics and western geography as qualitative differences (without actually testing it) but not being at the geographic heart of the opioid epidemic or having MMJ laws without operational programs.
The concern is legit—cannabis companies and budtenders need to be careful about the health claims they make—and future studies might find that the PNAS researchers were right to doubt the broad correlation between MMJ laws and reduced mortality. However, the researchers seemed to frame the data in a selective way that welcomes the same criticism that Humphreys in particular levels against cannabis studies with positive findings. They allowed confounding variables to negate the data for recreational states but not for MMJ states, which led to a finding that aligned with their pre-existing beliefs.
An even playing field that doesn’t pick and choose what variables to include would arguably produce a very different conclusion, namely that greater access to cannabis represents the strongest association (relative to the study estimates) with reduced overdose deaths.
Still, neither conclusion belongs on a billboard because 1) all the researchers agree the estimates were not significant, 2) causation remains unclear and 3) we need more high-quality research, but this statement cuts both ways. Cannabis-adverse researchers, politicians and bureaucrats don’t let the lack of research keep them from making outrageously untrue and misleading statements. Historically speaking, a handful of billboards that overstate pro-cannabis findings doesn’t compare in the slightest to decades of fallacious propaganda, research restrictions and the attitude that cannabis is guilty until proven innocent.
Instead of being so concerned about the 2014 study, the PNAS researchers might want to ask themselves why cannabis naysayers have lost credibility with a public that now supports full legalization by a two-to-one margin.
Hint: It’s not the billboards.
