This study indicates that states that legalized marijuana use for medical purposes have significantly higher rates of marijuana use and of marijuana abuse and dependence. The results for marijuana use were found at the state level in two national datasets, the NESARC and the NSDUH, and at the individual level in the NESARC. In addition, in the NESARC, respondents living in states with medical marijuana laws had significantly higher prevalence of marijuana use disorders (abuse/dependence) as defined by DSM-IV. However, in the NESARC, among those who were using marijuana, there was no increase in odds of abuse or dependence, suggesting that any relationship detected between state medical marijuana laws and marijuana abuse/dependence is explained by differences in marijuana use.
