The United States and Canada are both engaged in cannabis policy reforms with a number of US states legalizing or decriminalizing use, possession, cultivation, and sale, and the Federal Government of Canada poised to legalize cannabis in 2018. Perhaps the most contentious debate in Canada has been about setting the legal minimum age for access to the substance, following the recommendation from Canada’s Federal Task Force on Cannabis Legalization and Regulation of age 18 (Government of Canada, 2016), their rationale being that setting the age of access lower will divert youth access from illicit, unregulated markets to a safer and tightly regulated supply, while reducing the numbers of youth charged for possession and entering the criminal justice system. This is particularly important as Canadians aged 18–24 are the demographic with the highest prevalence of cannabis use (Spithoff et al, 2014). The recommendation for age 18 was also intended to harmonize the age for legal access to cannabis with alcohol and tobacco, which is 18 or 19 years across Canada’s provinces and territories.

This policy issue intersects with the interests of Neuropsychopharmacology readership because of the ways in which neuroscience expertise is frequently cited by those who favor a higher age of access. For example, policy-makers often make generalizations such as ‘evidence from brain scientists shows cannabis is harmful to developing brains’. Not only does this overstate scientific consensus about how cannabis use during adolescence affects brain structure and functioning, it also neglects key confounders in adolescents’ substance use, including the effects of alcohol and polysubstance use (Weiss et al, 2017). To the contrary, the updated Lower Risk Cannabis Use Guidelines recently published in Canada avoid specifying an age, but instead prioritize addressing how early onset and greater frequency of use during adolescence are likely to be associated with harms and future problematic use (Fischer et al, 2017). Without casting cannabis as benign or ‘safe’, as adolescent substance-use researchers we are concerned about the overriding emphasis on ‘protecting young brains’ being mobilized in the policy discourse, primarily by associations representing the health professions, stakeholders who hold sway and authority with the public but who are not themselves experts in cannabinoid science.

Another important consideration we have identified through our youth-engaged research is that telling youth that something is harmful to the brain requires a nuanced approach to make it an actionable prevention strategy, with concrete steps that can be taken to make the use smarter and safer, and to minimize potential harms (Moffat et al, 2013; Jenkins et al, 2017). As the move towards decriminalization and legalization policies gains momentum both within and beyond Canada, we call for greater involvement of our neuroscience colleagues in media forums, in policy conversations, and in collaborative prevention research with members of the health and social science research community—to dispel misinformation and to support the development of evidence-based cannabis prevention for adolescents in the context of drug policy reform.

Funding and disclosure

Grant funding was provided by ‘the Canadian Institutes of Health Research’. The authors declare no conflict of interest.