Teenagers less likely to take cannabis in states where it's legal, study finds.
Thursday 11th July 2019
Harriet Alexander, New York Telegraph
High school students are ten per cent less likely to take cannabis in states where it has been legalised, a new study has found.
A team of academics, led by Mark Anderson, an associate professor at Montana State University, found that, despite concerns, the legalisation had actually decreased use among students.
Ten states and the District of Columbia have legalised recreational use of marijuana, following the lead set by Colorado and Washington in 2014. Illinois last month announced that it will in January become the 11th state to legalise the drug.
Researchers found an eight per cent drop in the number of high school students who said they used marijuana in the last 30 days, and a nine per cent drop in the number who said they had used it at least 10 times in the last 30 days.
The research was published in the medical journal JAMA Pediatrics on Monday. "Just to be clear we found no effect on teen use following legalisation for medical purposes, but evidence of a possible reduction in use following legalisation for recreational purposes," said Mr Anderson.
"Because our study is based on more policy variation than prior work, we view our estimates as the most credible to date in the literature."
The team looked at data from 1993 to 2017 on about 1.4 million high school students in the US, taken from the Centers for Disease Control and Prevention's annual national Youth Risk Behavior Surveys.
The researchers took a close look at self-reported marijuana use in the surveys among the students as well as survey responses in areas where medical or recreational marijuana was legalized.
The researchers examined the responses before and after the marijuana laws were implemented.
Mr Anderson said that, as legalisation was increasing, further research was necessary.
"Because many recreational marijuana laws have been passed so recently, we do observe limited post-treatment data for some of these states," he said.
"In a few years, it would make sense to update our estimates as more data become available."
Bonnie Halpern-Felsher, professor of pediatrics in Stanford University's Division of Adolescent Medicine in Palo Alto, California, said that the data contradicts other studies that found marijuana use was unchanged.
The Colorado division of criminal justice office of research and statistics found that the proportion of high school students in the state who said they used marijuana ever in their lifetime or in the past 30 days remained statistically unchanged from 2005 to 2017.
"I think the big question is why," she said. "Why are they seeing in this national dataset decreases - pretty significant decreases - when other studies are finding no difference?
*"The other question is, are youth getting the message about the fact that using marijuana during adolescence is more harmful because of their brain development?
"Given the legalisation, we need more education around marijuana or cannabis use for youth - and we don't really have a lot of education."*
The researchers wrote in the paper that one possible explanation could be that in states where recreational marijuana is legal, "it is more difficult for teenagers to obtain marijuana as drug dealers are replaced by licensed dispensaries that require proof of age."
Nationwide the overall prevalence of marijuana-only use among youth in the US since the early 1990s increased from 0.6 per cent in 1991, to 6.3 per cent in 2017, according to a study published in the American Journal of Public Health on Wednesday.
New York and New Jersey are expected to be the next states to legalise the drug.