Grant: CIHR Fellowship

Cannabis is the most widely produced, distributed and consumed illicit drug worldwide. Canada and many other countries are introducing new regulatory approaches to cannabis, including legalization. Although most research has focused on the harms of cannabis use, recent evidence suggests that cannabis use may alter specific high-risk drug practices. This research indicates that cannabis is often used as a substitute for high-risk substances such as cocaine, heroin or prescription opioids. However, these studies have not examined the impact of cannabis use over time and it is uncertain how the legalization of recreational cannabis will influence rates of high-risk drug use, infectious disease risk and addiction treatment. Given the recent legalization of recreational cannabis in Canada and the current opioid overdose crisis, identifying the impacts of cannabis use on high-risk drug use will be important for informing clinical and public health practice, as well as policy. The purpose of this research program is to describe how changing cannabis access and use influences the development of high-risk drug use patterns and addiction treatment. To accomplish these objectives, we will use data from three long-running community-recruited cohort studies in Vancouver, Canada, which will be supplemented by linked administrative data on participation in addiction treatment. These cohorts are operated by the BC Centre on Substance Use and include over 3,700 individuals who use illicit drugs, including high rates of cannabis use (>40%). Importantly, these studies include participants at different points in their drug use career, including at-risk youth at early stages of illicit drug use and older adults who use illicit drugs and tend to be more involved in addiction services. The diverse composition of these cohorts provide the opportunity to study the effects of cannabis use on the trajectory of high-risk drug use across the lifespan of active illicit drug users.