Teens in California Are Consuming More Cannabis Following Legalization, Study Finds

The legalization of adult-use recreational cannabis in California has impacted the state’s teens, according to new research from the Prevention Research Center of the Pacific Institute for Research and Evaluation.

For the new study, published in the Journal of Studies on Alcohol and Drugs, the researchers gathered data from state-wide surveys of over 3 million students and found significant increases in lifetime and past-30-day cannabis use among nearly all demographic groups post-legalization.

The finding stands in contrast to those from other recent studies, which have found falls in teen cannabis use in states that have legalized adult-use cannabis.

“The apparent increase in marijuana use among California adolescents after recreational marijuana legalization for adult use in 2016 is surprising given the steady downward trend in marijuana use during years before legalization,” Mallie J Paschall, a senior research scientist at the Prevention Research Center and the lead author of the new study, said in a statement.

Significant increases in use seen in traditionally low-prevalence groups

Paschall and his colleagues examined data taken from the California Healthy Kids Survey – the largest statewide self-administered survey of health-related attitudes in the nation. Looking at responses from the 2010-11 to the 2018-19 year groups, this new study included data on over 3.3 million 7th, 9th, and 11th grade students from over 3,800 schools across all 58 counties in California.

Certain questions gauged the teens’ cannabis use; they were asked how often they consumed cannabis in the past 30 days and over their lifetime. After combining these responses with demographic information provided by the students, the Prevention Research Center research team analyzed changing trends in marijuana use across different demographic backgrounds.

They found significant increases in cannabis use. Following legalization, teens were 18 percent more likely to consume cannabis at any point in their lives and were 23 percent more likely to consume in the past 30 days. Marked increases were also seen in overall cannabis use frequency in regular users across nearly all demographic subgroups.

The researchers also highlighted the relatively greater increases seen in cannabis use within groups that historically had lower usage rates.

“I was somewhat surprised to see relatively greater increases in the prevalence of marijuana use among younger adolescents (7th graders) relative to 9th and 11th graders, among females versus males, among non-Hispanic versus Hispanic youth, and among Whites versus youth in other racial groups,” said Paschall.

“In other words, there were greater increases in marijuana use prevalence after recreational marijuana legalization among youth in ‘low-risk’ groups, which is concerning.”

More research needed to determine the causes of change

Given the nature of the study, the researchers can't say for certain what is causing this spike in cannabis use. But given the increase in traditionally "lower-use" groups, they theorize that the legalization of recreational cannabis has normalized the drug, which has somehow trickled down into increased youth use.

However, while the legalization of adult-use cannabis was a significant policy change for the state, it has not been the only major change in recent years. The 2018 Farm Bill’s legalization of hemp and hemp-derived CBD products might also have affected the teens’ perceptions of cannabis products. The researchers also note reports of a growth in vape use among teens and say that the popularity of vaping could be further influencing behavior.

“Recreational marijuana legalization may be contributing to an increase in marijuana use among adolescents in California, but we need to do further research to confirm this,” Paschall said. “We also need to look more closely at what’s happening at the local level, because there is a lot of variation in marijuana policies in communities across California and the United States. Also, we need to know more about how adolescents are getting marijuana and what forms of marijuana they are using, since there is such a great variety of cannabis products available.”

“I’m interested in whether recreational marijuana legalization for adult use may affect use among adolescents, possibly by changing norms regarding the acceptability of marijuana use, perceived harms of marijuana use, or availability of marijuana to youth,” he added.

A spotlight on teen cannabis use

While the present study shows an increase in the use of cannabis following state legalization, other studies have found the exact opposite.

In 2019, one multi-state study looking at cannabis usage rates in young people actually found slight declines in past-30-days cannabis use for occasional and regular users following recreational legalization in their state.

“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 that study, told Analytical Cannabis at the time.

“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.”

Yet, another study published in JAMA Psychiatry later that year uncovered a 25 percent relative increase in the number of teens using cannabis problematically post-legalization. Although this study did note a slight fall in the prevalence of cannabis use disorder (CUD) among young adults aged 18 to 25.

Researchers in this field often stress the need for further studies exploring the complex effects of legalization. Only with more information will lawmakers and public health officials be able to create the policies and initiatives that are needed to better support adolescents affected by drug use.

“There are, indeed, important social benefits that legalizing marijuana can provide, particularly around issues of equity in criminal justice,” Magdalena Cerdá, an associate professor at NYU Langone Health and lead author of the JAMA Psychiatry paper, said in a statement following its publication.

“Our findings suggest that as more states move toward legalizing marijuana for recreational use, we also need to think about investing in substance use prevention and treatment to prevent unintended harms – particularly among adolescents.”