A new study that reverses thought on the benefits of medical marijuana in preventing opioid deaths is evidence more cannabis research is needed, says one of the sponsors of the measure that legalized medical marijuana in North Dakota.

A paper describing the new study was published online June 10 in Proceedings of the National Academy of Sciences. Researchers at the Stanford University School of Medicine found legalizing medical marijuana doesn’t reduce the rate of fatal opioid overdoses.

That’s counter to a 2014 study published in the Journal of the American Medical Association that found lower rates of fatal opioid overdoses in states where medical marijuana was legal. States with medical cannabis laws had a 24.8% lower annual opioid overdose mortality rate compared with states without medical cannabis laws.

The 2014 study has been touted by supporters of legalized marijuana and others as a reason for legalization.

Anita Morgan of Fargo, a lead sponsor of North Dakota’s medical marijuana measure, approved by voters in 2016, said the study’s findings were among advocacy points cited in pushing for passage. She’s not convinced those findings should be totally dismissed by the latest research but supports further research to better understand the medical benefits of marijuana.

“It’s under-funded, under-researched, head in the sand. It’s time for the federal regulators to wake up, smell the coffee, reschedule it and get some research done,” she said.

Marijuana is classified by the federal government as a Schedule I drug, indicating it has high potential for abuse with no accepted use in medicine. That classification discourages research and can hinder access to funding.

The Stanford research was funded by the National Institutes of Health and the U.S. Department of Veterans Affairs.

Stanford researchers confirmed the findings from the 2014 study, but in extending the data to 2017, when more states had legalized medical marijuana, they found a higher rate of opioid overdose deaths. Medical marijuana is legal in 47 states.

The Stanford research compared states with restrictive medical marijuana laws with those that allow recreational marijuana and found no correlation between opioid overdose deaths and the level of restriction. Instead, researchers speculate the 2014 results reflected characteristics and conditions in the states that legalized early.

Morgan cites another study posted online last September by the National Center for Biotechnology Information that found evidence to support use of cannabis to ease opioid withdrawal symptoms, reduce opioid consumption, ameliorate opioid cravings, prevent opioid relapse and reduce overdose deaths.

“The compelling nature of these data and the relative safety profile of cannabis warrant further exploration of cannabis as an adjunct or alternative treatment for OUD (opioid use disorder),” the study authors concluded. The study was authored by researchers at the University of Missouri and Washington University School of Medicine, both St. Louis.

The article noted the evidence has prompted some states and private treatment centers to begin to include cannabis as part of opioid treatment protocols.

Recently, the University of Texas Medical Branch at Galveston revealed study results finding fewer opioids prescribed in states that have allowed the use of medical marijuana, based on information from a major database of de-identified, privately insured adults.