Cannabis legalisation not linked to increase in teen use, says study

A new study, funded by a US government drug agency, has found that legalising cannabis for adult-use did not lead to an increase in consumption among teenagers. 

The study, which was carried out at the University of Washington with funding from the National Institutes of Drug Abuse (NIDA) in America, explored whether state legalisation of adult-use cannabis was associated with increased use among adolescents. 

A total of 18 US states have now legalised cannabis for adult-use, with many countries across the globe, including in Europe expected to follow suit.

Concerns around an increase in consumption among young people are often cited as reasons to avoid more liberal cannabis laws.

The new research paper, published earlier this month in the American Journal of Preventive Medicine, examined whether cannabis legalisation predicted changes in the probability of cannabis use among those aged 13–18 years.

It specifically looked at data from three longitudinal studies on past-year cannabis consumption and frequency of use among adolescents between the years of 1999-2020 in Oregon, New York and Washington State.

Within this time period Washington and Oregon both legalised cannabis, the former in 2012 followed by Oregon in 2014. New York passed the legislation last year, but retail dispensaries are not yet up and running.

The findings

According to the paper the change in legislation was ‘not significantly related to within-person change in the probability or frequency of self-reported past-year cannabis use’ among adolescents.

Researchers also compared teenagers who grew up in states with differing legislations.

Young people who spent more of their adolescence in states where cannabis was legal were ‘no more or less likely to have used cannabis at age 15 years’ than those who spent ‘little or no time’ in such a state. 

The authors concluded that rates of adolescent cannabis use are ‘holding steady after non-medical cannabis legalisation for adults’.

However they recommended ‘ongoing surveillance’ and further studies to explore the effect of legalisation on different demographics and on younger children whose parents consume cannabis.

This study builds on previous NIDA-funded research which found adolescent cannabis use is decreasing, even in states where cannabis is legal.

Results from the 2021 Monitoring the Future survey reported ‘significant decreases’ in use of substances commonly used in adolescence, including alcohol, cannabis and vaped nicotine.

Elsewhere in Colorado, which was one of the first states to legalise cannabis in 2013, adolescent use also appears to be declining.

The Colorado Department of Public Health and Environment’s (CDPHE) Healthy Kids Colorado Survey found that young people were 35% less likely to use cannabis in 2021 than in prior years

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