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Medical Marijuana Laws Don't Cause Teens to Start Smoking Pot, Study Finds

The research, which pulled together 24 years of data, found that "medical marijuana laws do not account for increased use of marijuana in US adolescents."
Photo by Joerg Carstensen/EPA

Researchers may have just debunked one of the biggest arguments used by anti-pot campaigners against the legalization of medical marijuana with a new study that finds there was no substantial increase in adolescents using the drug after states legalized it for medical use.

The Columbia University study, published in the medical journal Lancet Psychiatry, pulled together 24 years of data nationwide which shows that adolescents between 13-18 were just as likely to use pot illegally as they were after medical marijuana became legal.


The study "showed no evidence for an increase in adolescent use of marijuana in the year of passage of a medical marijuana law, or in the first or second years after passage," Dr Deborah Hasin, professor of epidemiology at Columbia University's Medical Center, and her colleagues wrote in the paper. "These findings, consistent with those from earlier studies, provide the strongest empirical evidence yet that medical marijuana laws do not account for increased use of marijuana in US adolescents."

Currently 23 states and DC have medical marijuana laws on the books. Researchers found that in those states adolescents generally used pot more, but the reason for that could be attributed to a number of other factors that need to be further investigated. The passage of legislation alone was not enough to attract more teens to use pot, the researchers found.

Related: Acknowledged That Marijuana May Help Fight Brain Tumors

The findings are consistent with previous studies on California, which was the first state to pass a medical marijuana bill in 1996. At the time, the law — coupled with proven scientific evidence that pot adversely affects adolescent development — sparked fears that young people would suddenly flock to smoke shops and toke on bongs in droves. Those perceptions still exist nearly 20 years later.

"That fear, raised in 1996, when California passed the first effective medical-marijuana law, has not come true," Dr. Joycelyn Elders, a former US Surgeon General wrote in a 2004 op-ed in the Providence Journal. "According to the official California Student Survey teen marijuana use in California rose steadily from 1990 to 1996, but began falling immediately after the medical-marijuana law was passed."


Researchers at the Marijuana Policy Project (MPP) also found that the rate of youth marijuana use also dropped across other states with medical marijuana laws use in the nine years after the passage of California's pot initiative.

"A considerable body of data shows that no state with a medical marijuana law has experienced an increase in youth marijuana use since their law's enactment," MPP's legislative analyst Karen O'Keefe and Mitch Earleywine, Associate Professor of Psychology at the State University of New York at Albany, wrote in a 2005 report. "All have reported overall decreases of more than the national average decreases — exceeding 50 percent in some age groups — strongly suggesting that enactment of state medical marijuana laws does not increase teen marijuana use."

Although marijuana use (both recreational and medical) is banned at the federal level, the justice department has issued a memo essentially allowing states to pass their own pot laws without repercussions. A federal bill to legalize medical marijuana was introduced in March this year.

Related: 'The time has come': Medical marijuana legalization bill makes it to the federal level

The latest research to look at the correlation between medical marijuana laws and teen cannabis use examines a much larger data sample taken from annual Monitoring the Future studies conducted between 1991 and 2014. Those studies looked specifically at 8th, 10th, and 12th graders, factoring in variables that could potentially affect the results, including ethnicity and race, age, socioeconomic status, number of students in each grade, and whether the school was private or public or in an urban or suburban area.


The results showed a significant decrease in marijuana use among 8th graders after passage of medical marijuana laws, while the risk of pot use among 10th and 12th graders showed no notable change.

The researchers explained the reason may be because the older children may have "already formed attitudes towards marijuana" and weren't influenced when states introduced medical marijuana laws, while the younger children were perhaps more susceptible to influence and education and "were less likely to view marijuana as recreational after states authorized its use for medical purposes."

But this is simply conjecture, and the researchers ultimately concluded that lawmakers and campaigners should spend less time debating the legalization of medical marijuana and instead direct resources to find out what is actually causing more teens to smoke pot.

"The identification of large-scale societal factors that increase the risk of early use is crucial," they wrote. "Our study findings suggest that the debate over the role of medical marijuana laws in adolescent marijuana use should cease, and that resources should be applied to identifying the factors that do affect risk."

Related: A Woman Lost Custody of Her Son After He Defended Medical Marijuana in School

Follow Liz Fields on Twitter: @lianzifields

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