Marijuana legalization foes often point to charts showing that when perceptions of harm among teenagers drop, pot use increases. That’s no longer the case, according to new data.

The 2014 Monitoring the Future survey finds a continued decline in perceptions of risk associated with using marijuana among eighth-, 10th- and 12th-grade students, along with declining or stable rates of marijuana use.

Each age group reported lower levels of lifetime, annual, monthly and daily use of marijuana in 2014 – though some of the numerical declines were not statistically significant.

Dr. Wilson Compton, deputy director of the National Institute on Drug Abuse, says the data suggest new thinking is needed about the relationship between perceptions of harm and teen pot use.



"That's what’s been surprising to me and other researchers: We've now had five years of consistent declines in perceived harmfulness and the use rates have been reasonably steady – or dropping slightly this year," Compton says. "This is a bit of a puzzle and speaks to a different relationship of these phenomena than we've seen in the past."

Among high school seniors, 16.4 percent said occasional marijuana use puts the user at great risk, down from 19.5 percent last year and 27.4 percent five years ago. About 21.2 percent of high school seniors said they smoked pot in the past month, down from 22.7 percent last year.

The survey, conducted annually by University of Michigan researchers and funded by the National Institute on Drug Abuse, does not provide state-level data, so it's not possible to determine if legalization in Colorado and Washington influenced local use rates.

Colorado's state health department reported in August, however, that high school use in that state did not increase in 2013 – the first full year pot possession was legal for adults 21 and older – despite a decreased perception of harm.



Last week, at a Heritage Foundation-hosted event against marijuana legalization, the co-founder of anti-legalization group Smart Approaches to Marijuana, Kevin Sabet, directed his audience to charts showing a close historical relationship between perceptions of harm and teen pot use.

Sabet, a former presidential drug adviser, says he's not convinced that the data scuttles the association.

"Though there were no significant increases in past-month marijuana use in 2014 [versus] 2013, data from 40 years of research show a consistent correlation between perception of risk and actual use," he says. "No one can credibly claim that since marijuana use is not up in 2014 versus 2013 that perception of harm and use are not related – one year a trend doth not make."



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Compton, however, says, "I'm not surprised by a one-year difference, but the fact that we've now seen declining perceived harm for several years and the use rates are holding steady is an anomaly."