Opioid-related deaths in Massachusetts continue to decline in 2017, according to the latest data from the state. The reasons for the decline, as with any trend in public health, are likely to be complicated. But some advocates for marijuana legalization cite it as additional evidence that legalization results in fewer opioid deaths.

Multiple studies have shown a correlation — states that have legalized marijuana have had lower rates of opioid deaths — but any scientist will tell you correlation alone doesn’t mean cause-and-effect. 

We can’t say legal weed is responsible for the lower rates of death from opioid overdose, at least not without a lot more detailed study. But we can look at what the latest science and research tells us about the effect cannabis can have on the opioid problem.

Kids are still warned of marijuana’s danger as a gateway drug, and drug war hawks like current Attorney General Jeff Sessions have suggested that legal pot will make the opioid problem worse. But Elizabeth Dost, a healthcare executive and longtime registered nurse here in Boston, says marijuana isn’t a gateway drug — it’s an ‘exit drug’ — patients can use it to get off opioid painkillers.   

One patient Dost said she recently encountered was a professional woman about 50-years-old who “had a myriad of health complications that included significant pain for which she took Percocet. And she was able to come off of her Percocet with use of cannabis.”

This is one of the ways advocates say medical marijuana could help with the opioid problem — patients using cannabis instead of opioid drugs.

Amanda Reiman works for Flow Cana, a cannabis distribution company in California; as a lecturer at the University of California in Berkeley, she led a study that examined how patients there were using medical marijuana. They found that “about 76 percent of the medical cannabis population said they were using cannabis as a substitute for prescription drugs.” Of those, 95 percent said “cannabis was a much better experience for them in managing their pain and their symptoms than opiates or other medications.”

 Still, Reiman says it’s a leap to say legal pot is responsible for the overall decline in opioid overdose deaths. 

“We have people saying, ‘Yes, cannabis has helped me. I used to be on all of these opiates and now I'm not. And I was addicted to this, and now I'm not,’" she said. "Those anecdotes are very moving but they're also not causation.”

Dr. Yasmin Hurd, a neurologist and head of Mt. Sinai’s addiction center in New York, says we need a lot more research about marijuana’s relationship to opioid addiction. 

“There clearly [are] some benefits for different cannabinoids and even some marijuana strains, perhaps, but those are not conclusive as yet,” said Hurd, who leads a multi-disciplinary team of scientists studying addiction. 

But Hurd says one compound in some strains of cannabis has shown particular promise: cannabidiol, or CBD.

“That has been shown to have in one way even neuroprotective effects, decreasing anxiety,” Hurd said. “And it doesn't have any rewarding properties there's no hedonic effects associated with using cannabidiol.”

Meaning CBD doesn’t get you high.

“Some of our own studies have shown that it may be potentially beneficial in decreasing craving in heroin abuse,” Hurd said.

Aside from its potential in decreasing craving for opioid addicts, Amanda Reiman says that medical marijuana can be as effective as a first-line treatment for opioid withdrawal.

“We know that it helps with nausea,” she said. “We know that it helps with pain. We know that it can have an impact on muscle seizures and other types of tremors. So, I think that cannabis is a very suitable medication to help people move through that withdrawal phase.”

But Dost says that in Massachusetts, it’s not easy for patients to figure out what might work for them.

“They really are not utilizing nurses in dispensaries to help the dispensary and to help walk patients through this event of using cannabis,” Dost said.

In Massachusetts, you need to get a referral from a qualified doctor to get medical marijuana, but you don’t get a prescription — no script from a doctor telling you what strain of cannabis to take, how to take it, what dosage, or how often.

“Without rigorous scientific studies conducted, we're never going to get there,” she said.

Even if doctors and nurses get more involved, Hurd said they still lack the information they need to effectively prescribe the drug.

“The irony of it, the catch-22 of this whole situation, is that people have voted and now we have so-called medical marijuana,” Hurd said. “And people are consuming these drugs. Yet still the federal regulations for research to be conducted with marijuana which is considered a schedule one drug. [That has] limited the amount and the type of research that can be done.”

Advocates like Dost are working to change some of the rules around medical marijuana in Massachusetts to get nurse practitioners more involved, but she’s worried the needs of medical marijuana patients will be forgotten now that recreational pot has been legalized.