“No evidence” that legalisation encourages teen cannabis use

Legalisation laws are not associated with a rise in young people’s consumption of cannabis, say researchers in the US.

According to a new study, neither the enactment of medical cannabis legalisation laws nor the establishment of dispensaries in the US, are associated with any upticks in young people’s use of cannabis.

A team of investigators from John Hopkins University in Baltimore, as well as with Harvard University and the Massachusetts Cannabis Control Commission reviewed cannabis use trends in more than one-million adolescents over a nearly 25-year period.

The data, published in the journal Substance Abuse, was consistent with prior studies and found no evidence of an increase in cannabis use among teenagers between 1991 and 2015.

This study used state Youth Risk Behavior Survey (YRBS) data collected from participants in grades 9-12 from 1991 to 2015 in 46 states in the US.

The main outcome assessed was past 30-day adolescent cannabis use.

Authors concluded: “This study found no evidence between 1991 and 2015 of increases in adolescents reporting past 30-day marijuana use or heavy marijuana use associated with state MML [medical marijuana law] enactment or operational MML dispensaries.”

Authors added: “Our main finding was that adolescents residing in states with MMLs had significantly lower odds of past 30-day (“current”) marijuana use compared to adolescents residing in non-MML states (6 percent). In grade stratified analyses, the 9th graders had 9 percent lower odds, whereas there were no differences for other grade levels.”

Commenting on the study’s findings, NORML Deputy Director Paul Armentano said: “These data, gathered from 46 states over more than two decades, show unequivocally that medical cannabis access can be legally regulated in a manner that is safe, effective, and that does not inadvertently impact young people’s habits. 

“These findings should reassure politicians and others that states’ real-world experience with medical cannabis is a success from both a public health and a public safety perspective.”