In one of the biggest studies of its kind to date, researchers have found no evidence to suggest the legalization of marijuana results in an increase in youth use. In fact, the study points to a strange potential decrease in teen marijuana use following the implementation of recreational use laws.

As the wave of marijuana legalization continues to spread around the globe, scientists are continually tracking data from some of the earliest American states to implement these laws. The highly politicized debate over the effect of legalization includes everything from crime to healthcare, but one of the big unanswered questions regarding legalization is whether it increases adolescent and teen use.

This new study took its data from a biennial youth health survey conducted by the Centers for Disease Control and Prevention (CDC). Compiling survey data from 1993 to 2017, the final sample size included over 1.4 million high school students from across the United States. During the survey period 27 states instituted medical marijuana laws and seven states adopted recreational use laws.

The results revealed medical marijuana laws resulted in no changes at all to levels of youth marijuana use. But recreational laws, on the other hand, strongly correlated with a slight decline in youth use. Frequent youth marijuana use, as defined by at least 10 uses in the prior 30 days, dropped by nine percent in states following the adoption of recreational laws.

This is one of the first studies to suggest a potential decrease in youth marijuana use following recreational legalization, with prior studies having generally suggested teen and youth use remains stable following legalization. The researchers hypothesize the drop in youth use could be related to the suggestion that, following legalization, "it is more difficult for teenagers to obtain marijuana as drug dealers are replaced by licensed dispensaries that require proof of age."

While this is certainly a fine hypothesis, it is difficult to imagine teen marijuana use drops following legalization due to it simply being harder to obtain the drug. After all, how difficult is it for a teenager to obtain alcohol while in high school? Perhaps a more interesting hypothesis is a suggestion put forth last year by evolutionary biologist Nathan Lents, arguing a teenager's interest in marijuana drops when the stigma or taboo is removed.

"Most drug deterrence initiatives repeat the refrain that drugs are harmful and taboo," Lents writes in Psychology Today. "But this is precisely what makes them so attractive to teens, especially teenage boys. In their minds, it frames drug use as an opportunity to show off to others and advertise fitness. The greater the stigma against marijuana, the more valuable the costly signaling is for teenagers who dare to buck the taboo."

Of course, this new study is only one datapoint amongst many, and it makes no claim to asserting any causal connection between a state adopting recreational marijuana laws and the drop in youth use. In fact, general teenage drug use in the United States has been consistently dropping for the past 20 years, so there is a reasonable argument to be made suggesting recreational marijuana laws have made very little difference to overall youth drug use trends.

As Canada comes up to its first anniversary of countrywide recreational marijuana legalization, and other countries such as Mexico and New Zealand present similar progressive possibilities on the horizon, what is inarguably clear is that we will certainly have more data available to better answer these important questions very soon.

The new study was published in the journal JAMA Pediatrics.