Dr. Italia V. Rolle, PhD and Dr. Tim McAfee, MD Office on Smoking and Health National Center for Chronic Disease Prevention and Health Promotion CDC

More Cannabis Outlets, More Cannabis Use By Young Adults

MedicalResearch.com Interview with:

Eric R. Pedersen, Ph.D. Adjunct Behavioral Scientist, RAND Associate Professor of Psychiatry and Behavioral Sciences Keck School of Medicine University of Southern California

Dr. Pedersen

Eric R. Pedersen, Ph.D.
Adjunct Behavioral Scientist, RAND
Associate Professor of Psychiatry and Behavioral Sciences
Keck School of Medicine
University of Southern California

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

Response: In November of 2016, CA voted to legalize cannabis for sale and possession to adults 21 and older for recreational use. It wasn’t until January of 2018 that stores in most parts of LA County (we call these “outlets”) were legally able to begin selling recreational cannabis. We were collecting data from about 2,500 young adults in LA County as part of a longitudinal study (Principal Investigator Elizabeth D’Amico at RAND) and were able to look at cannabis use and intentions assessed at a period prior to the opening of the recreational cannabis outlets (pre-January 2018) to a period when those outlets were open (after January 2018). It has been suggested that once cannabis was more available for recreational purchase (and not just for medical purposes among those enrolled in CA’s medical marijuana program), use of cannabis among young adults would increase. 

MedicalResearch.com: What are the main findings?

Response: Our study did not allow us to look at that, but we did find that the greater number of outlets selling cannabis near a young adult’s home in LA County (within 4 miles), the more likely they were to use cannabis, even after accounting for whether they had used prior to cannabis being available in these outlets (pre-January 2018). More specifically, we found that the number of licensed cannabis outlets around where a young adult lived was associated with a number of cannabis outcomes, like heavier use and intentions to use, whereas a great number of unlicensed outlets within a 4 mile radius of young adults’ home was associated with heavier and more problematic use. The young adults in our sample had about 6 licensed outlets within a 4 mile radius of their home, with an average of about 7-8 unlicensed outlets near their home within 4 miles. 

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

Response: At the time of our study in early 2019, we found that most of the outlets in LA County selling cannabis were unlicensed. About 62% of the 430 were found through an online search and drive-by observations were unlicensed. Although the number of licensed outlets around one’s house associated with their own use and intentions to use in the future, the number of unlicensed outlets was associated with heavier use and more symptoms of cannabis use disorder.

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

 Response: Now that cannabis has been available for recreational purchase in LA County for about three years, it will be important for longitudinal studies to look at how young adults’ cannabis use has changed (decreased, increased, stayed the same) over that period. Though multiple studies look at this, it will be important for these studies to look at how the number of cannabis outlets around one’s home can account for the changes we are seeing. 

No disclosures. Thanks for the interest.


Pedersen, E.R., Firth, C.L., Rodriguez, A., Shih, R.A., Seelam, R., Kraus, L., Dunbar, M.S., Tucker, J.S., Kilmer, B. and D’Amico, E.J. (2021), Examining Associations Between Licensed and Unlicensed Outlet Density and Cannabis Outcomes From Preopening to Postopening of Recreational Cannabis Outlets. Am J Addict. https://doi.org/10.1111/ajad.13132 



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Last Updated on January 15, 2021 by Marie Benz MD FAAD