Legal cannabis and opioid overdoses: It’s complicated.

MILWAUKEE — In Wisconsin, some have argued that legalizing cannabis will lead to a drop in opioid overdoses, since people can use marijuana to treat their pain rather than opioids.

Others have claimed the opposite — saying that legal cannabis will serve as a gateway drug to more potent substances.

What You Need To Know

  • Wisconsin and other Midwestern states have seen overdose deaths rise as fentanyl has become more widespread
  • Overdose data in the Midwest don’t show a clear link between cannabis laws and the opioid crisis
  • National studies are also mixed, with some researchers finding there is no cause-and-effect relationship
  • There are other public health measures to address overdose, like naloxone access and medication treatment

So what does the science say? As it turns out, there aren’t easy answers.

Here, we break down some of what we know — and what we don’t know — about the link between cannabis laws and opioid overdoses, in the Midwest and beyond.

A look at our region

In recent years, opioid overdoses have been on the rise across the country — and Wisconsin is no exception.

The rate of opioid-related deaths in the Badger State jumped by around 46% from 2018 to 2020, the Department of Health Services reports. And since 2014, the rate of emergency room visits related to opioid overdoses has more than doubled, according to DHS data.

Fentanyl has likely played a major role in that uptick as it has spread across Wisconsin and beyond, said Dr. Elizabeth Salisbury-Afshar, an associate professor at UW-Madison and a physician trained in addiction medicine.

“As it relates to opioids, we are seeing that there’s more and more fentanyl in the drug supply,” Salisbury-Afshar said. “And that is consistent nationally.”

So what about the role of cannabis laws? In the Midwest, the link isn’t obvious.

The states around Wisconsin form a patchwork of cannabis laws: Illinois and Michigan both allow recreational use. Minnesota only allows medical use. And Indiana and Iowa, like Wisconsin, don’t allow either recreational or medical cannabis.

Out of these states, Michigan, Indiana and Illinois have seen the highest recent rates of overdose deaths from synthetic opioids — which includes fentanyl — according to CDC data from 2017 through 2019.

That means two of the states with more permissive cannabis laws still had some of the highest per capita overdose deaths in the region. (Though both states only legalized recreational marijuana in the past few years, they’ve had medical cannabis laws for longer.)

For drug overdoses in general — beyond just synthetic opioids — the picture is also mixed.

Predicted overdose deaths in the prior 12 months have risen in Wisconsin and all of these neighboring states between November 2016 and November 2021, according to the latest available CDC estimates.

Minnesota (which allows medical cannabis) and Indiana (which doesn’t allow cannabis use) saw some of the highest percent increases in that time period — while Wisconsin and Illinois both saw rises of around 61%..

National research finds mixed results

In the US as a whole, research has been split on whether there is a link between legal cannabis and opioid overdoses.

One study from 2014 found that in states with medical cannabis laws, opioid overdose deaths rose more slowly than in states where cannabis wasn’t legal.

Some states used the study, which looked at data between 1999 and 2010, as promising evidence for opening up more medical cannabis programs, said Dr. Chelsea Shover, assistant professor at the UCLA School of Medicine.

But when Shover’s team later took the same models and applied them to a longer timeframe — bringing in data through 2017 — they found the opposite effect. States with medical cannabis laws actually saw faster increases in their opioid overdose deaths, their analysis found.

Shover’s team did not conclude that cannabis laws were actually making the overdose crisis worse. Instead, they figured the flip-flop in results meant that there was no real cause-and-effect relationship, she said.

“What that really suggests is that the issue of medical cannabis legalization and responding to opioid overdose are just two separate things,” Shover said.

The question of cannabis laws and opioid overdose has kept sparking new research in recent years.

One study last year suggested that counties with more cannabis dispensaries saw fewer opioid deaths. And another study concluded that when states implemented recreational cannabis laws, they saw drops in opioid-related ER visits — but the declines disappeared after six months.

Overall, a 2019 review of the research on this topic said that legalizing marijuana could lead to a “modest reduction” in opioid prescriptions, but described the scientific evidence as “inconsistent and inconclusive.”

For Shover, there are other reasons to argue for legal cannabis — like evidence that it can help with some medical conditions outside of opioid use disorder. And she’s interested in other research that is examining whether parts of the cannabis plant could help treat opioid addiction on the individual level.

But she doesn’t think that trying to link legal cannabis with overdose declines on a state level is useful.

“There are really effective policies to combat opioid overdose,” Shover said. “That’s just not one of them.”

Other public health measures can help

Though scientists aren’t totally in agreement about the role of cannabis laws in the opioid crisis, there are a range of other ways that public health is working to prevent overdose deaths.

For one, Salisbury-Afshar said, there have been efforts across the country to keep tabs on fentanyl in the drug supply — including in Wisconsin, where fentanyl test strips were recently legalized. That’s important because the main risk from fentanyl is its unpredictability, she said.

“It is a potent opioid,” Salisbury-Afshar said. “But it’s really the fact that people don’t know what they’re getting when they get it that makes it so dangerous.”

Pushes to make the opioid-reversal medication naloxone more widely available can help save lives in the case of overdoses, she said.

And encourage people not to use alone is another important public health message, Shover said — especially with fentanyl, which is more potent and faster-acting than other drugs.

“In order to save someone’s life who’s having a fentanyl overdose, you have a very short window,” Shover explained.

On the individual level, Salisbury-Afshar pointed out that medication treatment has proven effective for opioid use disorder. The three FDA-approved medications are all linked with better outcomes for those with opioid use disorder, including making them less likely to resume drug use after treatment.

Medication shouldn’t be the only solution, though, Salisbury-Afshar said. She believes treatment plans should also offer other support systems, like counseling and peer services — not just a “one size fits all” solution, she said.

And in the long term, it’s important to support healthy families and communities so that people don’t reach the point of an opioid use disorder, Shover said.

Instead of viewing an addiction as a “moral failing” by one person, public health needs to recognize and work against all the factors that can lead to a substance use disorder — like trauma, mental health conditions and lack of opportunity, Salisbury-Afshar said .

“During the overdose crisis, we’ve been very focused on stopping the overdoses. Which we have to do, because there are way too many people dying,” she said. But “if we’re really going to make an impact in the long run, we have to start looking further upstream.”

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