Legal cannabis isn’t just raking in tens of millions in tax revenue every month. It isn’t just helping ease the suffering of patients with anxiety, depression, chronic pain and sleeplessness; and it isn’t just fun to use recreationally. Legal cannabis in Colorado and elsewhere in the U.S. may actually be reducing mortality rates.
That’s according to new research from Greta Hsu and Balázs Kovács published in The British Medical Journal (BMJ). Specifically, the researchers found that legal weed seems to be associated with fewer opioid overdose deaths in counties across the country that have legalized cannabis. It could be a consequential discovery, as the U.S. opioid crisis reaches unprecedented levels.
It’s a finding that adds to a growing litany of research at the intersection of cannabis and opioid usage. And it could help researchers better understand the complex supply-side of related drug markets — like those for cannabis and opioids.
“There’s this idea of a substitution effect, where people shift to using cannabis instead of relying on opioids,” explains Kovács, an associate professor at the Yale School of Management.
Anecdotal evidence shows that people make this trade-off: stories of people kicking pills in favor of flower and of patients avoiding opioids outright because they have access to alternative medication.
When it comes to hard data on that question, though, the available research has been inconclusive. One previous study, published in the Proceedings of the National Academy of Sciences of the United States of America, concludes that “if such relationships do exist, they cannot be rigorously discerned with aggregate data.” Another study, from Injury Epidemiology, suggests that “it remains unclear” whether or not any such relationship exists, and even goes as far as to say the medical benefits of cannabis legalization might not outweigh its impacts on “mental health and traffic safety.”
But there are also research papers suggesting that there is a significant effective correlation between the two drug markets; that legalizing cannabis has a notable and important impact on both opioid usage and overdose deaths. Those studies, however, are very broad and only explored the question at a state-level, Kovács says.
“The data has been really mixed so far,” he says.
That’s why he and Hsu designed an epidemiological study of their own to try to find out whether or not opioid-related overdose deaths rose or fell in states with medical and recreational legal cannabis, and if so, by how much.
In their study, they looked at data from 812 counties across 23 states (every U.S. county that allowed legal cannabis dispensaries to operate by the end of 2017). They then used weedmaps.com to compare the number of physical dispensaries in those counties with their corresponding opioid mortality rates from the Department of Disease Control and Prevention (CDC).
According to their findings, legalizing medical marijuana results in an 8% reduction in opioid-related mortality rates — and legalizing it recreationally results in a 7% reduction.
“Higher medical and recreational storefront dispensary counts are associated with reduced opioid-related death rates, particularly deaths associated with synthetic opioids such as fentanyl,” their study concludes.
While that cannot be assumed to be causal, Kovács says, it does suggest a potential association between more cannabis dispensaries and fewer opioid mortalities. Which opens up a host of other questions: Is that because people are more likely to get hooked on opioids if they don’t have an alternative? Or because cannabis users are just less susceptible to opioid addiction? Or are users in legal states simply getting safer weed than those in prohibition states?
“Where I live in New Haven, (Connecticut), there’s a lot of fentanyl overdose cases because the marijuana in black market cannabis joints is laced with fentanyl,” Kovács explains, which could account for the more statistically significant reduction in deaths from synthetic opioids, he says.
Kovács is the first to admit that the study has limitations, though. Foremost among them is the fact that the only figures they compared dispensary numbers against were the worst-case scenario: opioid-related mortality rates. Other, more nuanced effects aren’t reflected by these numbers, and are very challenging to pinpoint through aggregate data.
“There could be a lot of things under the surface we don’t see with this data,” Kovács says. “Like people who don’t die, for example, we don’t see [in this data].”
Nevertheless, this apparent relationship between legal cannabis and lower opioid-related deaths seems extremely hopeful, particularly in the wake of the COVID-19 pandemic and 2020, which saw the highest number of opioid overdose deaths in U.S. history — over 81,000. Having an alternative medicine that could potentially curb that dark trend is more important now than it’s ever been.