Cannabis use in Switzerland 2015–2045: A population survey based model

Background Alternative cannabis regulation models are discussed and implemented worldwide. A baseline scenario under the assumption of no policy or market changes may prove useful to forecast cannabis use and treatment demand and evaluate changes in legislation. Methods Based on data of the Continuous Rolling Survey of Addictive Behaviours and Related Risks on cannabis use, age, gender and nationality from 2011 to 2015, we used general estimating equation analysis to model lifetime and 30-days prevalence from 2015 to 2045 in Switzerland accounting for demographic trends. Results Lifetime prevalence of cannabis use is projected to grow from 28.3% (CI 95% 27.8–28.8) in 2015 to 42.0% (CI 95% 41.0–43.0) in 2045. 30-days prevalence would increase slightly from 2.70% (CI 95% 2.53–2.88) to 3.39% (CI 95% 3.11–3.66). Due to population growth, absolute numbers with past 30-day cannabis use are estimated to increase from 202,784 (CI 95% 189,534–216,035) to 314,302 (CI 95% 288,504–340,100). Among those aged under 30 years no substantial change in lifetime and 30-days prevalence of cannabis use is projected. Larger changes are estimated to occur in the age group 30+. The mean age of past 30-day cannabis users would increase for men with Swiss nationality from 30.3 to 38.7 years. Discussion Population-based survey data and demographic projections can be used to develop baseline scenarios of future cannabis use. Assuming no changes in cannabis legislation, growing absolute numbers of users will likely increase treatment demand. Cannabis use is estimated to increase among the group aged >30 years, which is currently underrepresented in clinical treatment and research. Our findings highlight the need for prospective baseline scenarios to evaluate the impact of legislative changes on cannabis use. Moreover, in Switzerland effective prevention and treatment interventions for cannabis use disorders are required even if cannabis legislation remains unchanged.