Did teen perception, use of marijuana change after recreational use legalized?

A dried flower bud of the Cannabis plant. Credit: Public Domain

Marijuana use significantly increased and its perceived harm decreased among eighth- and 10th-graders in Washington state following enactment of recreational marijuana laws, according to a UC Davis and Columbia University Mailman School of Public Health to be published online in JAMA Pediatrics. There was no change in use or perceived harm among 12th graders or among similar grades in Colorado.

The authors believe the study is the first in the nation to assess changes in teens' perceptions and marijuana use before and after legalized recreational use, and compare these attitudes and use in 45 other contiguous states where marijuana use is not legal.

The data showed that legalization of recreational marijuana use significantly reduced perceptions of marijuana's harmfulness by 14 percent and 16 percent among eighth and 10th graders and increased their past-month marijuana use by 2 percent and 4 percent in Washington state but not in Colorado.

Among states without legalized marijuana use, the perceived harmfulness also decreased by 5 percent and 7 percent for students in the two grades, but marijuana use decreased by 1.3 percent and .9 percent. Among older adolescents in Washington state and all adolescents surveyed in Colorado, there were no changes in perceived harmfulness or marijuana use in the month after legalization.

The researchers compared data on the perceived harmfulness of marijuana use to health and self-reported marijuana use for nearly 254,000 Colorado and Washington state students in the eighth, 10th and 12th grades who participated in the Monitoring the Future survey.

The survey measures drug, alcohol and cigarette use and related attitudes among adolescent students nationwide. The authors compared Washington and Colorado with 45 other states in the contiguous U.S. that did not legalize recreational marijuana use. In a sensitivity analysis, they also compared Washington and Colorado data with 20 states with but no recreational marijuana laws; results were unchanged.

The investigators attribute the lack of change in attitudes and marijuana use among teens in Colorado after legalization to a more robust commercialization effort prior to the law taking effect.

Colorado had very developed dispensary systems before recreational use became legal, with substantial advertising which youth were exposed to. Colorado also had lower rates of perceived harmfulness and higher rates of use compared to Washington state and other states where recreational use is not legal.

"While legalization for recreational purposes is currently limited to adults, potential impacts on adolescent marijuana use are of particular concern," said Magdalena Cerdá, an epidemiologist with the UC Davis Violence Prevention Research Program and first author of the study.

"Some adolescents who try marijuana will go on to chronic use, with an accompanying range of adverse outcomes, from cognitive impairment to downward social mobility, financial, work-related and relationship difficulties. We need to better understand the impact of recreational marijuana use so we're better prepared to prevent adverse consequences among the most vulnerable sectors of the population," Cerdá said.

While more targeted research is needed to determine the influence of legalized recreational marijuana use among adolescents and how well the Washington state and Colorado experiences can be generalized to the rest of the U.S., the authors believe that states considering legalized recreational use may also want to consider investing in evidence-based substance abuse prevention programs for adolescents.

The potential effect of legalizing marijuana for recreational use has been a topic of considerable debate since Washington and Colorado first legalized its use for adults in 2012. Alaska, Oregon and Washington, D.C., followed suit in 2014, and voters in California, Massachusetts and Nevada approved recreational use this past November.

"The perceived harmfulness of marijuana has declined sharply in the U.S. in the last few years, despite the fact that there are adverse consequences associated with marijuana use in some adults and in adolescents," said Deborah Hasin, a professor of epidemiology at Columbia University's Mailman School of Public Health and in psychiatry at Columbia University and principal investigator of the study.

"Epidemiologic monitoring of these consequences as more states legalize recreational use, and public education about potential health consequences, are important to protect ," Hasin said.

Cerdá noted that the study suggests that legalization of marijuana in Washington reduced stigma and perceived risk of use, which could explain why younger adolescents are using more marijuana after legalization.

"Other potential reasons for the increase in use include increased access to marijuana through third-party purchases, and lower price," Cerdá said. "Older adolescents may also have had their attitudes and beliefs about marijuana formed before recreational use was legalized, making it less likely their use would change after legalization."

Explore further

No uptick in marijuana use by adolescents after states pass medical marijuana laws

More information: JAMA Pediatr. Published online December 27, 2016. DOI: 10.1001/jamapediatrics.2016.3624
Journal information: JAMA Pediatrics

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Dec 27, 2016
The word "Reported" should be amended to the first sentence. Re-read that sentence like that and the truth of the situation might be more easily accessible to you.

Yes, it is true. If you ask children if they have done something illegal, they may lie to you about it. You will get more truthful results about actual drug use when the substances are decriminalized. This creates avenues for oversight, intervention, and treatment.

Too bad our government has arbitrarily decided to schedule marijuana in such a way that it cannot be legally tested for potential harmful effects. More "stick your head in the sand" regulations will not help Americans make proper decisions about their health. Sad that we have this wonderful tool called the scientific method and we cannot use it to evaluate a naturally growing plant. Seems as if the Luddites are running the show, much to the detriment of humanity.

Dec 27, 2016
Speaking of sticking your head in the sand, you conveniently ignored decades of research on the harmful effects of marijuana use. Here's a convenient summary to refresh your memory, which, sad to say, could have been hampered by marijuana use.


And here's one of many articles on marijuana and memory loss:


It's amazing how great marijuana is when you ignore all the bad stuff researchers have discovered.

Dec 28, 2016
We have literally 100,000's of thousands man-year's of experience with Cannabis.
So far, any effects on memory are so slight as to be difficult to measure.
Likewise, it's notoriously difficult to detect, objectively, any degree of impairment after Cannabis use among most people.
This is telling. It certainly is telling the youth and anyone else who listens, that cannabis, as a "problem" ,is a negligible one at the worst..

Dec 28, 2016
It's amazing how great marijuana is when you ignore all the bad stuff researchers have discovered.

Wow duped much? 70 years of goverment/corporate propaganda paid off.
All mammals have an endocannabinoid system we are alive because of it, mothers milk has cannabinoids in it. People are sick because they do not have enough that's why a drop can stop a grand maul seizure. They found canabinoids killed seven types of cancer in the seventies and cut funding because most reasearch was only funded to find negative results. Our government lists it schedule 1 no medicinal value yet has patents on the neuro protective benefits of cannabinoids in brain trauma injury. It's called market control, free markets only exist in fantasy. Legalized Cannabis would eliminate 30% of Pharmaceuticals over night and be a constituent in 50% of the remainder because of its therapeutic efficacy according to the top researcher with over fifty years of study.

Dec 28, 2016
I dunno did teens think that alcohol was less harmful after it was legalized?
And here's one of many articles on marijuana and memory loss
Here's a nice article from our favorite source about alcohol and memory loss

-dopers may forget the capital of Arkansas but at least they'll remember what they did last night-

Dec 28, 2016
Speaking of sticking your head in the sand, you conveniently ignored decades of ...

In fact for each study that you cite I could as easily cite a couple saying the complete opposite. And you also forget that the question is not whether marijuana is _perfectly_ good and healthy but how dangerous it is compared to other drugs like alcohol or coffee.

And you also have to take the social problems of the illegality into consideration: Is prosecution and prohibition an adequate tool? Does it have positive or negative social effects?

Here: http://www.drugwa...nds_v_US

Specifically interesting is the prevalence data: Here in Holland from the people who have used the drug less are likely to continue using it.

It also implies that young users are less likely to get in touch with other hard drugs as it is the case with street dealers.

Dec 28, 2016
EnricM makes a good point. If young people get marijuana from legitimate sources, it keeps them off the black market, and helps prevent them from already having a way to get harder drugs.

I could see young peoples perception being more easily altered at certain points in their growth (middle school) and not so easily later in life (12th graders).

Marijuana is not all bad. It is certainly less harmful than Alcohol, yet everyone acts like Alcohol is just fine. Marijuana is anti-inflammatory, and can help with arthritis and several other medical conditions. It is not chemically addictive, although it can be psychologically addictive.

The gateway drug argument is ridiculous, as alcohol is easily the primary gateway drug. The worst part about Marijuana is that it tends to rob a person's Ambition, but this is not universal and depends heavily on the person.

I'm just sick of Alcoholics being considered normal, and someone who smokes weed on a occasion is Unemployable!!!

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