Effects of recreational marijuana laws on the consumption of marijuana and other substances by age

Since 2012, ten states have legalized marijuana for recreational consumption for adults over the age of 21. Each adopting state (as well as 23 others) had previously legalized the use of medical marijuana for patients with a restricted set of health conditions. In this paper we estimate the effects of recreational (and medical) marijuana legalization on the consumption of marijuana and other drugs in the general population and for selected age groups. The data underlying our analysis come from the National Survey of Drug Use and Health’s Small Area Estimates. These data report state-by-age group level drug use estimates for an annual representative sample of the civilian, non-institutionalized population aged 12 and older living in the United States. We find that states adopting recreational marijuana see increases in the prevalence of past-year marijuana use of 9 percent for adolescents (ages 12-17), 12 percent for young adults (ages 18-25), and 19 percent among adults (over age 25). We find consistent results when estimating the impact on past-month marijuana use and first-time marijuana use. In contrast, we find that medical marijuana legalization does not have a large effect on the prevalence of marijuana use in any of the age groups or time frames in our study. We find some suggestive evidence that marijuana deregulation reduces alcohol use and increases cocaine use. Overall, our study suggests that recent efforts to legalize marijuana represent a real reduction in the extent to which government policies discourage marijuana use. Importantly, we show that marijuana use increases for adolescents (ages 12-17), an age group not legally allowed to purchase recreational marijuana and more likely to suffer negative health consequences from marijuana consumption. The results of our study may be useful for states that hope to experiment with packages of regulations that can raise or lower the level of marijuana use for particular age groups or the general population.