Commentary on Prince van Leeuwen etal. (2014): Tobacco and cannabis use

摘要

One of the most contested issues in drug and alcohol research has concerned whether or not there are progressions in substance use in which the use of one substance or drug increases the risks of using other drugs [1-4]. It has been hypothesized that the use of licit drugs such as alcohol and tobacco may predispose young people to use cannabis, and in turn cannabis acts a 'gateway' drug which encourages the use of other illicit drugs. There is now substantial evidence [3,5-9] that: (a) the use of cannabis usually precedes the use of other illicit drugs; and (b) this association cannot be explained as being due to third or confounding factors, suggesting some form of causal relationship between the use of cannabis and the use of illicit drugs. However, the mechanisms which explain this association remain unclear [5,7,8].