Study Finds No Relation Between Cannabis Legalization and Teen Use
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As an increasing number of US states continue to pass medical and recreational cannabis laws, organizations such as the American Academy of Pediatrics have raised concerns that this increased availability of legal cannabis to adults might have a knock-on effect on adolescent cannabis use. This topic has become an important area in public health research, with experts continuously reviewing possible associations between legalization and heightened teen cannabis use as increasingly more data become available.
Published this week in JAMA Network Open, a new study from Montana State University suggests that there is little evidence that medical or recreational cannabis legalization encourages adolescent cannabis use. On the contrary, the researchers identified a small decrease in the odds of teen cannabis use following medical cannabis law adoption.
No evidence suggesting legal cannabis encourages adolescent use
As of July 2021, recreational cannabis laws are on the books in 18 states plus Washington DC, with 37 states having approved some form of legal access to medical cannabis.
The most recently published data from the Youth Risk Behavior Survey (YRBS) includes post-recreational legalization sales era data from 10 states. The researchers used these data with multivariate logistic regression to estimate the association between legalization status and the odds of adolescent cannabis use at each survey wave.
“Consistent with estimates from prior studies, there was little evidence that RMLs [recreational marijuana laws] or MMLs [medical marijuana laws] encourage youth marijuana use,” the study authors concluded.
After adjusting the logistic regression models for various state and survey-wide indicators, the researchers found no associations between recreational cannabis laws and either reported current cannabis use or frequent cannabis use in the adolescent survey participants. Medical cannabis legalization was associated with a six percent decrease in the odds of current cannabis use and a seven percent decrease in the odds of frequent use in the years following medical cannabis law adoption.
After two or more years following recreational cannabis legalization, there was a decrease seen in the odds of cannabis use. However, the paper notes that the overall association between legal recreational cannabis and teen cannabis use was “statistically indistinguishable from zero.”
New study confirms previous findings
In 2019, the same research group behind the JAMA Network Open study published a similar research paper in JAMA Pediatrics, which assessed all states that had implemented medical or recreational cannabis laws and published YRBS data until that point.
This study was done using data from YRBS for 1993-2017, which was the most up-to-date dataset available to the researchers at the time. This early study included pre- and post-recreational sales era data from just three states. The new study, which covers the time period 1993-2019, includes seven states that are now able to report pre- and post-recreational data.
Both studies found no evidence supporting the notion that teen cannabis use increases following medical or recreational legalization. The earlier study also identified slight decreases in use following recreational legalization, but this finding was not upheld in the overall trends seen in this new JAMA Network Open study.
“I think the big takeaway is that we find no evidence that teen marijuana use goes up after legalization for medicinal or recreational purposes,” Mark Anderson, an associate professor at Montana State University and lead author of the study, told Analytical Cannabis after the publication of the 2019 paper.
“We view this as a very important result from a policy perspective because opponents often claim that teen use will skyrocket after these laws are passed. Based on our analysis, this has simply not been the case.”
Writing in the newly published JAMA Network Open study, the research authors acknowledge that this study is still fairly limited by the extent of the data it can review, simply because these cannabis policy changes are so recent. As time passes and more post-legalization data becomes available, future research efforts will be able to draw firmer conclusions on the relationship between legalization status and adolescent cannabis use.
Cannabis concentrates, advertisements also present concerns
State-level cannabis legalization is not the only teenage drug use risk factor being closely scrutinized by public health and policy experts.
Recently, Colorado introduced a bill that will impose limits on the number of cannabis concentrate products that medical cannabis patients can buy, in a move partially geared towards limiting teen access to high-strength cannabis products.
Speaking to the Denver Channel ahead of the bill’s signing, state attorney general Phil Weiser commented that “this legislation […] addresses that fact that our medical marijuana laws have enabled teen access to high potency marijuana.”
The bill also asks the Colorado School of Public Health to carry out a new review of scientific research related to the physical and mental health effects of high-potency THC products and lays the groundwork for a new public education campaign communicating the effects of high-potency THC products on the developing brain of adolescents.
One additional facet that comes with recreational cannabis legalization is the ability of cannabis brands in some states to publicly and legally advertise their products. Earlier this year, researchers at the University of North Carolina at Chapel Hill published a paper in the Journal of Studies on Alcohol and Drugs examining the effects of cannabis advertising on teen cannabis use habits.
They found that teens who were frequently exposed to billboard or storefront advertisements for cannabis products had seven times the odds of reporting “frequent” cannabis use (defined as using cannabis four or more times per week) and nearly six times the odds of having symptoms associated with cannabis use disorder, as compared to their peers who reported never seeing physical advertisements.
“Associations between ads and use may not stop at experimentation – ad exposure may facilitate progression toward problematic use, and their association may even be causal,” the UNC-Chapel Hill study authors concluded, warning that any potential collateral effect on youth should not be ignored as more states begin to accept recreational cannabis for adult-use.