LAUSR

It is important to take stock of what we really know about the dependency profile of cannabis. There is much that I would agree with in the review of this topic by Budney and colleagues [1]; however, I think there are some important factors that were missing from their analysis. First, it is not surprising that incidence and prevalence rates vary over time as most of the data these rates are derived from rely on selfreported observational surveys, with well-documented limitations associated with these methods [2]. This is amplified by the problems of disclosure and recall when interviewing people about use of cannabis. A further concern is the bias at play in the diagnostic manuals used to assess cannabis use disorder, for example, the Diagnostic and Statistical Manual has used criteria such as asking participants about operating machinery or driving trucks while under the influence of cannabis [3]. This sets the abuse criteria lower for men than women, so these maleorientated questions could account for some of the difference between male and female dependence. Gender differences are not limited to social factors as recent biological investigation offers some insights as to why women progress for cannabis exposure to dependence quicker than men [4]. The gender differences in pharmacokinetics for cannabis are still to be fully revealed and could inform the way dependence is assessed and defined in a more gender-sensitive way. Demonstrating how much cannabis dependence is influenced by consequences of use as much as the physiological effects of the drug, significant international differences in prevalence exist, a point which Budney and colleagues acknowledge. Overall, higher income countries also have higher population rates of dependence compared to lower income ones [5]. Regulatory approaches vary between countries as do enforcement measures applied when access to cannabis is restricted [6]. This adds to the distorted view we have of cannabis and the risks of dependence observed so far. The trend observed in some countries of increasing demand for treatment due to cannabis use could be due to several factors including rising potency, increasing acceptance of cannabis-related problems including dependence among users and treatment staff [7]. There appears to be a perception among many of those not in treatment but using cannabis frequently that treatment is not necessary to reduce cannabis use, with females significantly more likely than males to hold this view in one study [8]. This image of cannabis as a relatively benign drug is a view held not only by those using cannabis but also some treatment staff [9]. These are just some examples of the limitations associated with constructing accurate prevalence data on cannabis dependence. It is important that we collectively acknowledge these and ensure that they are given a more public airing otherwise we risk losing credibility on this issue with the public and those who use cannabis. There is more that we could do to improve the reliability of counting the number of people developing cannabis dependency at a time when many jurisdictions are reviewing and changing their regulatory approach to cannabis for medicinal and recreational reasons.