A study by University of Massachusetts Amherst researchers found that high school students are no more likely to use cannabis after legalization but were more likely to use cannabis if they perceived that their family or friends used cannabis themselves.

In a statement, Faith English, a doctoral candidate in the School of Public Health and Health Sciences and lead author of a paper published in a special issue of Clinical Therapeutics, said “It’s not news that youth are influenced by peers” but described the paper as “the first to look at these three particular roles within a person’s social network and then look at changes from pre- to post-legalization.”

“One of the million-dollar questions as cannabis policies are being implemented across the country is whether or not youth use increases after legalization. There’s a lot of concern that underage folks will start using cannabis with greater frequency. The brain isn’t done developing until about age 26, so the messaging really is to delay use until after that age.” — English in a press release

The researchers analyzed two datasets collected by a local substance use coalition who surveyed students at two eastern Massachusetts high schools. After comparing data from 2016, prior to broad cannabis legalization in the state, and after legalization in 2018 but before retail cannabis stores opened, the researchers found no statistically significant differences in the prevalence of past 30-day cannabis use. Among the 2016 participants, 19% of females and 27% of males reported past 30-day cannabis use. In the 2018 survey, 20% of females and 28% of males reported past 30-day cannabis use.

After legalization, there was an increase in the proportion of adolescents who reported a perception that their parents used cannabis (from 18% before legalization to 24% after legalization), even before retail stores opened. Perceived cannabis use by a best friend – compared to perceived use by a parent or sibling – had the largest association with cannabis use by adolescents, the researchers found.

The study notes that “the impact of availability of retail cannabis for adult use could affect the associations observed in this study, but that was out of the scope of the present investigation.”