Commentary on Burdzovic Andreas & Bretteville-Jensen (2017): Cannabis use opportunities-an under-researched factor in substance use epidemiology.

Abstract

Assessment of realistic cannabis use opportunities increases understanding of population-level changes in cannabis use behaviors among adolescents. In an era of rapidly changing cannabis policy, more nuanced models of cannabis use, exploring the pathway from first use opportunity to incident cannabis use, can inform the development of public health strategies. A large body of research has aimed to learn about the causal relationships that affect adolescent cannabis use decisions. During the last decade, much of this research has focused upon what effect, if any, the rapidly changing medical marijuana laws (MML) or recreational marijuana laws (RML) have on adolescent cannabis use. Within this body of literature, the standard model is investigated without reference to whether a person had a realistic cannabis use opportunity. This yields a simple model that combines two potential mechanisms of action, namely that MMLs and RMLs might increase adolescent access to cannabis or might increase willingness to use among those with opportunity. By explicating a model that differentiates realistic cannabis use opportunities from willingness to use the drug, given such opportunities, future analysis on the post-implementation effects of MMLs and RMLs can begin to explain a causal mechanism linking MMLs and RMLs to changes in cannabis use. In this issue of Addiction, Burdzovic Andreas et al. aimed to investigate the role of cannabis use opportunities in understanding adolescent cannabis use in a nationally representative sample of Norwegian adolescents 1. In this study, a realistic cannabis use opportunity was defined by a participant endorsing either (1) ever using cannabis in their life-time or (2) ever having the possibly to try cannabis without actually doing so. While such an investigation of cannabis use opportunities is not unique to this study by Burdzovic Andreas et al., the vast majority of extant studies have used some iteration of three similar questions about cannabis use opportunities: (1) has anyone approached you to sell you cannabis? 2; (2) have you ever had a chance to try cannabis if you had wanted to? 3-7; or (3) has someone either offered you cannabis or cannabis was present when others were consuming and you could have done so? 8. To the best of my knowledge, only a single study 5 has taken the question about cannabis use opportunities a step further and asked participants: ‘Who provided you with the opportunity to use (drug) for the first time?’, providing participants options that included: (a) I never had the opportunity; (b) I sought it myself; (c) a parent; (d) a sibling; (e) other family member; (f) a friend; or (g) another person. Such details about use opportunities are needed to inform interventions that can target the primary mechanisms giving rise to cannabis use among adolescents. Different types of use opportunities will necessitate different interventions. Use opportunities can vary substantially across several factors, including who is offering the drug (e.g. a close friend or family member or someone who is unknown to the person), how actively the drug is sought out (e.g. the person might seek out the drug or the person might receive an unsolicited offer to use the drug), how the drug is procured (e.g. it might be stolen from a family member's supply or directly offered for sale), the cost of the drug (e.g. free, $5, $20) and the drug's form (e.g. edible, inhalable smoke, inhalable vapor). Each mechanism will suggest a different intervention to target that specific mechanism of use opportunity. If, for example, adolescents who live in US states that allow the use of medicinal marijuana tend to report stealing cannabis from a family member's supply, an intervention might focus upon increasing the use of lockboxes or other physical barriers that can be used to secure medical marijuana in the house, whereas targeted information campaigns might be the primary mode of intervention to reduce an adolescent's willingness to use cannabis that is offered by a friend. When the type of use opportunities vary across different locations, the mechanisms that give rise to adolescent cannabis use opportunities will need to be elucidated fully to inform targeted interventions most accurately. In particular, specific questions about cannabis use opportunities are needed to clarify the mechanisms that have been hypothesized previously to link MMLs and RMLs to population changes in cannabis use (i.e. increased access to cannabis, changing cannabis use norms, or both). The study by Burdzovic Andreas et al. into the role of realistic cannabis use opportunities and willingness to use the drug, given such opportunities, highlights the need for a more nuanced model, with more specific questions about cannabis use opportunities, to explain marijuana initiation among adolescents. None. D.S.F. is supported by the National Institute on Drug Abuse (T32DA031099).