13 Nov Legalized Marijuana Has Potential To Increase Cannabis Use Disorder

MedicalResearch.com Interview with:

Dr. Cerdá

Magdalena Cerdá DrPH
Associate Professor and Director
Center for Opioid Epidemiology and Policy
Department of Population Health
NYU Langone School of Medicine 

MedicalResearch.com: What is the background for this study?

Response: Legalization of recreational marijuana use is increasingly enacted across US states and across the world. In the US, 11 states and D.C. have legalized recreational use of marijuana, while 33 states and D.C. have legalized medical use of marijuana. In light of these changes, we need to know the impact that recreational marijuana legalization has on marijuana use.

To our knowledge, our is the first study to look at the impact that recreational marijuana legalization has had on both use and cannabis use disorder among different age groups. 

MedicalResearch.com: What are the main findings?

Response: After examining usage following the enactment of marijuana legalization in 2012 to 2015, we found that:

1) Enactment of recreational marijuana legalization in 2012 to 2015 was followed by a small increase in cannabis use disorder among adolescents (from 2.18% to 2.72%) – this increase was 25% higher than that for participants in the  same age group in states that did not legalize recreational marijuana  use.

2) Among adults aged 26 or older, past-month marijuana use after legalization was 26 percent higher than in non-recreational states. Past-month frequent use rose by 23 percent, and past-year problematic use increased by 37 percent.

3) Among young adults aged 18 to 25, there was no difference found in past-month, frequent or problematic marijuana use.

However, it should be noted that we did a sensitivity analysis, to see how robust these particular findings were to unmeasured confounding – that is, to what extent could these findings be explained by a third factor that was more likely to occur in states that legalized marijuana and that was associated with marijuana use. With this sensitivity analysis, we found that if an unmeasured factor occurred at the same time or before recreational marijuana legalization and increased the risk of cannabis use disorder among adolescents slightly, this could explain the observed association between legalization and adolescent cannabis use disorder. This means we need to track trends in adolescent cannabis use disorder post-legalization over a longer time period, and across more states that legalize recreational marijuana use, to see whether there is indeed a robust increase in cannabis use disorder in this age group following legalization of recreational marijuana use. The findings on adults were more robust to unmeasured confounding.

MedicalResearch.com: What should readers take away from your report?

Response: Legalization of marijuana use has the potential to provide important social benefits, particularly around issues of equity in criminal justice. However, the potential for frequent marijuana use and cannabis use disorder is an important public health concern that we should be tracking, and it suggests that as states legalize recreational marijuana use, we also need to think about the investment in substance use prevention and treatment that we need to put in place to prevent unintended harms.

MedicalResearch.com: What recommendations do you have for future research as a result of this work? 

Response: In future studies, it will be important to look at how different types of approaches to legalization adopted by different states impact marijuana use, and how legalization affects different modes of consumption of marijuana (i.e., marijuana with different THC levels, edibles, vaping, smoking, etc). We should also investigate the pathways through which legalization might impact marijuana use, and how legalization affects use of other drugs, including alcohol, tobacco and opioids.

This study was funded by the National Institute on Drug Abuse grant R01 DA037866, provided to Dr. Silvia Martins (Columbia University).  

Citation:

Cerdá M, Mauro C, Hamilton A, et al. Association Between Recreational Marijuana Legalization in the United States and Changes in Marijuana Use and Cannabis Use Disorder From 2008 to 2016. JAMA Psychiatry. Published online November 13, 2019. doi:https://doi.org/10.1001/jamapsychiatry.2019.3254

Last Modified: [last-modified]

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Last Updated on November 13, 2019 by Marie Benz MD FAAD