Thursday, May 17, 2018


Does legalization increase marijuana use: From Duh! To Huh?

Whether or not Oregon’s July 2015 legalization of marijuana use for recreational purposes affected marijuana use rates sounds obvious, but is it? When told that the law increased marijuana use, many people said, “Duh! If its legal more people will buy it and use it.” But when told that it didn’t, many people said, “Duh! People who used will keep using, and people who didn’t use won’t start now just because its legal.” How can two opposite conclusions seem so obvious? Indeed, the effects these laws may be having are not clear at all. Studies of adolescents in Washington and Colorado have found mixed evidence after legalization, with some groups showing increases in rates of use and others showing no changes. Other research on college students has found increases in rates of use after legalization, but only for the subgroup of students who recently binged on alcohol. Furthermore, marijuana use rates have been increasing steadily across the country regardless of legality, and residents of states with legalization often showed higher rates of marijuana use even before their law passed. So, teasing out the truth is not a matter of simply comparing use rates before and after legalization. To illuminate these issues, David Kerr, Associate Professor in SPS will work as a co-investigator on a New Investigator Award with Dr. Harold Bae in the OSU College of Public Health and Human Science. The grant award was made by the Oregon Medical Research Foundation. Together, Drs. Bae and Kerr will study the extent to which recreational marijuana legalization is linked to changes in marijuana, tobacco, alcohol, and other substance use rates among college students in Oregon relative to their peers nationwide. They will do so using survey data collected from hundreds of thousands of college students across the country from 2008-2018. Identifying the magnitude of any changes will have important public health implications for young adults… obviously.