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Research Letter
December 19, 2018

Prevalence of Cannabis Use in Youths After Legalization in Washington State

Author Affiliations
  • 1Multnomah County/Oregon Public Health Division, Portland, Oregon
  • 2RAND Corporation, Santa Monica, California
  • 3Washington State Liquor and Cannabis Board, Olympia
  • 4Department of Population Health, School of Medicine, New York University, New York
JAMA Pediatr. 2019;173(2):192-193. doi:10.1001/jamapediatrics.2018.4458

In November 2012, voters in Washington legalized nonmedical (retail) cannabis for people aged 21 and older. Markets opened in July 2014. The effect of this change on cannabis use among youths is of public health concern.

Cerdá et al1 analyzed data from the nationally representative Monitoring the Future survey (MTF) and used difference-in-differences methods to compare cannabis use prevalence trends among youths in Washington with use in states without legalization of recreational marijuana. Because the MTF is not designed to provide state-representative estimates, the article generated covariate-adjusted modeled prevalence estimates for each state. The article suggested complex association between legalization and cannabis use among youths: increases in prevalence among Washington 8th and 10th graders, but not among 12th graders, relative to use in states without legalization of recreational marijuana.