Study Suggests Legalizing Pot Increases Adolescent Use, Except When It Doesn't

No significant changes detected in Colorado or among high school seniors in Washington; eighth- and 10th-graders in Washington are a different story.


JAMA Pediatrics

A new analysis of survey data finds that marijuana legalization was associated with more cannabis consumption among eighth- and 10th-graders in Washington but not among 12th-graders in that state or among Colorado students in any of those three grades. The study, published yesterday by JAMA Pediatrics, thus provides ammunition to both sides in the debate about how legalizing marijuana for adults affects adolescent use.

Voters in Colorado and Washington approved marijuana legalization in November 2012. Using data from the Monitoring the Future Study, U.C.-Davis epidemiologist Magdalena Cerdá and her colleagues looked at risk perceptions and past-month marijuana consumption in the three years preceding legalization (2010-12) and the three years following legalization (2013-15). They compared trends in Colorado and Washington to trends in the 45 contiguous states that did not legalize marijuana for recreational use during this period. They found no significant differences in Colorado or among high school seniors in Washington. But eighth- and 10th-graders in Washington deviated significantly from the national trends in risk perceptions and marijuana use.

In Washington the share of students who said occasional marijuana use poses a great or moderate risk (a dubious claim) fell from 74.9 percent to 60.7 percent among eighth-graders and from 62.8 percent to 46.6 percent among 10th-graders. Those changes were more than twice as big as the average drops in the 45 comparison states. Past-month marijuana use by eighth-graders did not rise significantly in Washington, but it fell significantly in the other states. The prevalence of past-month marijuana use among 10th-graders did rise significantly in Washington, from 16.2 percent to 20.3 percent, while falling in the rest of the country.

Assuming that the deviations among eighth- and 10th-graders in Washington have something to do with legalization, Cerdá et al. say, the mechanism is unlikely to be diversion from legal buyers, since state-licensed marijuana stores did not open in that state until July 2014, halfway through the post-legalization study period. But they argue that legalization may have changed attitudes toward marijuana in a way that encouraged adolescent use. "Our findings suggest that legalization of recreational marijuana use in 2012 reduced stigma and perceptions of risk associated with marijuana use," the researchers write. "A shift in social norms regarding marijuana use may have, in turn, increased marijuana use among adolescents in Washington." They suggest that older students' attitudes were unaffected because they were already well-formed.

As for why there is no evidence of this phenomenon in Colorado, Cerdá et al. note that the medical marijuana industry had a firmer legal basis there than in Washington prior to 2013, which may have made it more visible and more likely to shape teenagers' views of the drug. "Colorado had a very developed medical marijuana dispensary system prior to legalization, with substantial advertising, to which youth were already exposed," they write. "Washington, on the other hand, did not provide legal protection to medical marijuana stores. Therefore, the degree of commercialization and advertising of these collectives was substantially lower than in Colorado."

That explanation seems pretty speculative, especially since Cerdá et al. note that medical marijuana laws are not associated with increases in adolescent marijuana use. In fact, they make a point of comparing Colorado and Washington to states that allow only medical use and find differences similar to those identified in the broader analysis, "indicating that the effects we found are specific to legislation permitting recreational use." It is plausible that legalizing marijuana for recreational use would have a bigger effect on adolescent attitudes and behavior than legalizing it for medical use does. But it seems suspiciously convenient that in Colorado, the state where recreational retailers have been operating the longest, the opposite is supposedly true.

It is also worth noting that Colorado, the state where Cerdá et al. found no significant change in adolescent marijuana use, is the example that prohibitionists preferred to cite until recently, based on data from the National Survey on Drug Use and Health (NSDUH). That survey measured an increase in marijuana use by teenagers after legalization in Colorado, but the change was not statistically significant. The latest NSDUH numbers indicate that marijuana use by Colorado teenagers declined after state-licensed marijuana retailers began serving recreational customers. According to NSDUH, adolescent marijuana use also fell in Washington during that period.

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  1. You can’t trust stoner teens to fill out a survey at all, much less truthfully. Legalization is a gateway to liberty, anyway.

    1. When I was a teenager, in the 1970’s, I read up on illegal drugs a fair amount. Most of it was from the public library, so it had a strong prohibitionist sane overall, but I did notice that the more thoughtful books were less accepting of the mainstream narrative. I also had asset to sources of the countercultures ‘drugs are mostly wonderful’ narrative. My conclusion? 99% of all ‘drug war’ discussion – FROM BOTH SIDES – is utter pigswill.

  2. If it was a survey about meth the checkboxes on the Scantron would be scribbled oh-so-perfectly, and the one with smudge outside borders would be surrounded by blood from teen trying to wipe it away for hours along with the spider and attention spans would be too long for some questions like just a run-on sentence of the mind that never stops because that stupid spider ruined by Scantron smudge son-of-a-bitch I need a cigarette because aliens would be so cool if they hate ice cream.

  3. I knew this kid who started smoking dope in high school, then studied philosophy at a cut rate college while high on adderal, and then he became a successful (if shlumpy) editorial writer at a national news magazine though he was better known for his drunken clown rapping and then he died after choking on his own spittle after an overdose of xanax and oxy after returning home from a vapers anonymous meeting.

    Don’t do drugs, kids.


  4. Maybe it is parents’ responsibility to keep their kids from using pot and not the government’s? Parents taking responsibility for their children. What a crazy idea.

    1. Not to mention balancing concerns about certain age cohorts holding more permissive attitudes toward pot, and the reality that criminalizing pot use puts people of all ages through the legal system mangler. Gee, which is more worrisome?

  5. Any time I see “survey of teenagers” in a study, I stop reading. Did anyone actually honestly answer any survey they took part in when they were a teen? I don’t recall answering any surveys when I was young, but if I did the school would probably have a drug crisis team in place shortly after receiving the results.

  6. I would love to see a survey of people pro and anti marijuana legalization, asking why they were pro or anti.

    Because I know my reasoning is basically that people should be allower to do what they want with their bodies and lives. So data like this is only interesting at best to me. So I would love to see other people’s reasoning as I have noticed in general people don’t agree with my stance.

  7. Our school did a survey back in the early 70s. A friend of mind got wind of it 3 days before it was due to happen. We convinced our whole class that it would be cool to pretend that we hadn’t used any and even didn’t even know anybody who had ever taken drugs. Our teachers were very impressed with the results and told us so.

  8. Who fucking cares, I don’t care if it increases in use among toddlers. I really don’t care at all. Freedom MUST NOT be infringed because of fear mongering. Not to mention, the REAL questions. How often are these adolescents using it? Occasional use is fine, even for children, just like alcohol. If very frequently, why? More than likely because of shit parents or the shit educational system, not the young people themselves, who are not as stupid or impulsive as people seem to think. However, the way to solve shitty parents or shitty schools is usually removing power from those who want to keep it and increasing freedom, so they target the substance to gain more power and control.

    So I say again, who fucking cares if it increases in use among adolescents?

  9. It’s nice that they included the error bars on the graphs. Even though the error bars on the “Non-RML States” chart are simply unbelievable, it should be obvious from the chart that there is no statistically significant correlation between legalization and underage usage rates.

    Also, the error bars are much, much larger than the graphs indicate because the studies are based on teenagers self reporting.

  10. If legalizing something had no effect on its use, that would be a huge indictment of the governments ability to do anything, so I sorta doubt that’s what the majority of politicians want.

  11. They’re too busy playing the “choking game” to smoke weed.

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