MedicalResearch.com Interview with:
Dr. Magdalena Cerda
Magdalena Cerda, DrPH, MPH
Vice Chancellor’s Chair in Violence Prevention
Associate Director, Violence Prevention Research Program
UC Davis Violence Prevention Research Program
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The potential effect of legalizing marijuana for recreational use has been a topic of considerable debate since Washington and Colorado first legalized its use for adults in 2012. Alaska, Oregon and Washington, D.C., followed suit in 2014, and voters in California, Massachusetts and Nevada approved recreational use this past November.
In our study, we examined changes in perceived risk of marijuana use, and in use of marijuana among school-attending adolescents, in Washington and Colorado, following legalization of recreational marijuana use, and compared pre- to post-legalization changes in these two states to changes in the 45 contiguous US states that had not legalized recreational marijuana use.
Marijuana use significantly increased and its perceived harm decreased among eighth- and 10th-graders in Washington state following enactment of recreational marijuana laws. There was no change in use or perceived harm among 12th graders or among similar grades in Colorado.
In particular, the data showed that legalization of recreational marijuana use significantly reduced perceptions of marijuana’s harmfulness by 14 percent and 16 percent among eighth and 10th graders and increased their past-month marijuana use by 2 percent and 4 percent in Washington state but not in Colorado. Among states without legalized marijuana use, the perceived harmfulness also decreased by 5 percent and 7 percent for students in the two grades, but marijuana use decreased by 1.3 percent and .9 percent. Among older adolescents in Washington state and all adolescents surveyed in Colorado, there were no changes in perceived harmfulness or marijuana use in the month after legalization.