New Meta-Study Shows Legalizing Marijuana Doesn’t Increase Youth Cannabis Use

The new analysis investigates the impact of marijuana legalization on rates of marijuana use.

Statewide marijuana legalization does not increase rates of cannabis use in adolescents, according to a recent study published in the journal Current Addiction Reports.

Since California legalized the use of medical marijuana in 1996, 29 other U.S. states have also done so. Nine of those states have also legalized the possession and use of recreational marijuana by adults at least 21 years of age.

To investigate the effects of expanding statewide legalization on rates of cannabis use, researchers from the University of Queensland, the University of New South Wales, and Kings College London conducted a meta-analysis of 55 existing studies that investigated marijuana use trends following legalization.

Previous reports indicate that the loosening of marijuana laws does not encourage use by adolescence. In fact, as legalization has expanded throughout the U.S., teen cannabis use is at a 22-year low.

A meta-analysis, the researchers explain, can “potentially detect weak effects that may not be present in all or any of the individual studies.”

Just like the findings in individual studies, however, the researchers concluded that teen marijuana use does not increase after a state legalizes marijuana.

The studies that have been done, the researchers explain, “suggest that the passage of [medical marijuana laws] has not increased cannabis use among teenagers during the periods after their passage that has been studied to date.”

Adult Use Rises While Cannabis Use Disorder Drops

Legalization does appear to increase marijuana use by adults. The study found that the frequency of marijuana consumption by adults increased after states legalized medical marijuana.

The researchers note that a majority of this growth was likely associated with increasing numbers of adults who obtained a doctor’s recommendation and legally used medical marijuana through their state’s program.

The new meta-analysis also looked at whether rates of cannabis use disorder – an addiction condition characterized by compulsive cannabis use despite clinically significant impairment — were impacted by legalization.

While the researchers assumed that the rates of adult marijuana use following legalization would lead to higher rates of cannabis use disorder, their findings revealed that the opposite was true.

“Despite the increase in the prevalence of adult cannabis use, the prevalence of cannabis use disorders among adults in the past year did not change (remaining at 1.5 percent [from 2002 to 2004]]”, the researchers wrote in the study.

“More surprisingly still, the prevalence of [cannabis use disorder] among adults who used cannabis in the past year declined from 14.8 percent in 2002 to 11.0 percent in 2014,” they added.

While their study didn’t explore the reasons why cannabis use disorders decreased following legalization, the researchers did present a couple of theories. One was that lower rates of marijuana use by those underage, who are more prone to developing addiction, may have played a role.

Find the entire study, “Has the Legalisation of Medical and Recreational Cannabis Use in the USA Affected the Prevalence of Cannabis Use and Cannabis Use Disorders?,” at SpringerLink.

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