Cannabis policy: Time to move beyond the psychosis debate
March 11, 2010
Researchers, research funders and policymakers should give greater voice to the risks and harms associated with particular cannabis policies and to the evaluation of alternative regulatory frameworks. Given the decades of research and experience with cannabis prohibition, it seems reasonable to reorient the cannabis policy debate based on known policy-attributable harms rather than to continue to speculate on questions of causality between cannabis use and mental illnesses such as psychosis, depression, and related disorders, that will not be definitively answered any time soon
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Despite the widespread use of cannabis, it remains difficult to quantify the extent of health-related harms associated with its consumption, though researchers have noted that potential associations exist between cannabis use and mental illness, respiratory diseases, and chronic dependence (Kalant, 2004). Heavy cannabis smokers may be at particularly high risk of respiratory complications (Kalant, 2004), though experts have recently questioned the strength of this association (Tashkin, 2009). Cannabis use may also be implicated in causing dependence to the drug amongst heavy users (Hall & Degenhardt, 2009).
Scientists continue to investigate potential associations between cannabis use and mental illnesses such as psychosis, depression, and related disorders (Moore et al., 2007). In this context, the recent review by McLaren, Silins, Hutchinson, Mattick, and Hall (2009) in The International Journal of Drug Policy provides a useful overview of the last 5 years of observational research findings on the potential association between cannabis use and psychosis.
We should stress that we do not wish to be dismissive of the recent review by McLaren et al. (2009), which provides a useful overview of the state of the research on cannabis and psychosis. However, we feel that this latest in a series of reviews clearly delineates the present scientific limits of the debate on the potential association between cannabis and psychosis, and we argue, as have others, that overemphasis on this question by policymakers has distracted from more pressing issues (Degenhardt et al., 2007; Macleod et al., 2006). Clearly, current cannabis policies have failed to stem an increase in purity and consumption in a variety of settings. As such, researchers, research funders and policymakers should give greater voice to the risks and harms associated with particular cannabis policies and to the evaluation of alternative regulatory frameworks. Given the decades of research and experience with cannabis prohibition, it seems reasonable to reorient the cannabis policy debate based on known policy-attributable harms rather than to continue to speculate on questions of causality that will not be definitively answered any time soon (Macleod et al., 2006; Moore et al., 2007).
