A recent investigation by Columbia University’s Mailman School of Public Health found that the implementation of medical and recreational marijuana laws across various states did not result in noteworthy changes regarding opioid-related issues for the overall population. Notably, the study indicated a reduction in opioid-related outcomes among individuals who used cannabis following the introduction of medical marijuana laws. However, there were no significant changes observed after the implementation of laws for both medical and recreational marijuana. These results are published in the International Journal of Drug Policy.
By the end of 2019, 32 states had independently enacted medical marijuana laws (MCL). All states that later adopted recreational marijuana laws (RCL) had first passed MCL.
The research team reviewed data from the National Survey on Drug Use and Health (NSDUH) between 2015 and 2019 to understand the link between cannabis laws and opioid-related problems, focusing on prescription opioid misuse and heroin use.
This study adds to existing research on how MCLs alone and the combined effect of RCLs and MCLs impact opioid misuse and DSM-IV diagnosed opioid use disorder, both generally and among those with prior cannabis use. It expands upon several recent analyses involving NSDUH data.
“This study is the first to examine how cannabis legislation influences opioid outcomes among individuals who used cannabis in the previous year, particularly those who began using it before legal changes in their state,” stated Silvia Martins, MD, PhD, a professor of Epidemiology at Columbia Mailman School. “There has been considerable debate about whether the initiation of medical and recreational cannabis laws could lead to decreased prescriptions for opioid painkillers, reduced opioid use, misuse, opioid disorders, and even overdoses in the U.S.”
Martins went on to say, “When we compared individuals in states with only medical cannabis laws to those in states without any marijuana legislation, we observed an inconsistent trend of decreased opioid-related problems, especially among cannabis users. This trend was not reflected in states with recreational cannabis laws, suggesting that MCLs might be associated with decreased opioid use in cannabis users. However, further research is essential to validate and build upon these findings.”
Overall, the implementation of MCLs and RCLs did not seem to lead to significant changes in opioid-related concerns. However, there was an observed decrease in opioid misuse among individuals who reported using cannabis in the past year in states with MCLs compared to those without such laws. Meanwhile, the introduction of RCLs did not show any notable changes in opioid outcomes beyond those seen with MCLs.
During the study period from 2015 to 2019, about 282,768 individuals participated in the NSDUH. Of these, 4 percent indicated they had misused opioids in the past year, while 1.3 percent reported misuse in the previous month. Approximately 3 percent met the criteria for past-year DSM-IV opioid use disorder (OUD) encompassing both abuse and dependence. The prevalence of opioid misuse and use disorder was significantly higher among individuals who had used cannabis in the past year (15 percent) compared to non-cannabis users.
While certain reductions in opioid misuse and use disorder were noted in states with solely MCLs, these were limited to individuals who had consumed cannabis in the past year and started using it before cannabis laws were enacted. No similar trends were identified in states with both RCLs and MCLs. “Our findings emphasize the potential beneficial effects of MCLs, and future studies should continue to monitor changes in opioid-related harm as cannabis legalization evolves,” said Emilie Bruzelius, PhD, a post-doctoral fellow in the Department of Epidemiology at Columbia Mailman School and co-author of the study.
“Our results generally indicate that the establishment of RCLs and MCLs provides few benefits regarding substance misuse reduction. Ongoing monitoring of trends concerning RCLs and MCLs remains essential,” remarked Martins. “It’s important to note that fewer states have enacted RCLs alongside MCLs than those that have adopted MCLs alone, and most of these laws are relatively recent. Thus, the long-term consequences of RCLs and MCLs may become clearer as more states implement these regulations and as research continues beyond their introduction. Additional studies are required to explore opioid use among individuals obtaining cannabis from both medical and recreational dispensaries.”
Co-authors of the study include Christine Mauro and Kara Rudolph from Columbia Mailman School; Julian Santaella-Tenorio, Katherine Wheeler-Martin, and Magdalena Cerda from NYU Grossman School of Medicine; Anne Boustead from the University of Arizona; Hillary Samples and Stephen Crystal from Rutgers University; Deborah Hasin from Columbia Mailman School and the Columbia Department of Psychiatry; David Fink from the New York State Psychiatric Institute; and Corey Davis from NYU Grossman School of Medicine and the Network for Public Health Law in Minnesota.
The research received funding from NIH-NIDA grants R01DA045872, T32DA031099, K01DA049950, and K99DA055724.
