Widening acceptance of and access to medical marijuana in many U.S. states raises questions about how availability of marijuana in communities affects incidence and prevalence of marijuana use. A new study conducted in California examined whether the presence and density of medical marijuana dispensaries and delivery services affected patterns of marijuana use in 50 mid-sized cities in that state. Analyzing data from telephone surveys of nearly 9,000 people, the study authors found that participants’ current (past-year) marijuana use and frequency of use (although not lifetime use) was positively related to density of medical marijuana dispensaries and availability of delivery services (i.e., per roadway mile) in their city. After controlling for city-level measures of community social behavior and social disorder, only the association between density of storefront dispensaries and marijuana use outcomes remained. The authors note that it cannot be inferred from these associations whether greater availability in a community drives greater use or whether increased demand in some communities drives availability. Ongoing research showing changes in marijuana use and availability over time will be necessary to answer this question.
Examining the relationship between the physical availability of medical marijuana and marijuana use across fifty California cities, Freisthler B, Gruenewald PJ. Drug Alcohol Depend. 2014 Oct 1;143:244-50.. - http://www.ncbi.nlm.nih.gov/pubmed/25156224