Cannabis Liberalization and Adolescent Cannabis Use: A Cross-National Study in 38 Countries

Yuyan Shi,Michela Lenzi,Ruopeng An,Christopher Mark Doran

doi:10.1371/journal.pone.0143562

Yuyan Shi, Michela Lenzi + Show 2 more

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https://doi.org/10.1371/journal.pone.0143562

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Abstract

AimsTo assess the associations between types of cannabis control policies at country level and prevalence of adolescent cannabis use.Setting, Participants and DesignMultilevel logistic regressions were performed on 172,894 adolescents 15 year of age who participated in the 2001/2002, 2005/2006, or 2009/2010 cross-sectional Health Behaviour in School-Aged Children (HBSC) survey in 38 European and North American countries.MeasuresSelf-reported cannabis use status was classified into ever use in life time, use in past year, and regular use. Country-level cannabis control policies were categorized into a dichotomous measure (whether or not liberalized) as well as 4 detailed types (full prohibition, depenalization, decriminalization, and partial prohibition). Control variables included individual-level sociodemographic characteristics and country-level economic characteristics.FindingsConsiderable intra-class correlations (.15-.19) were found at country level. With respect to the dichotomized cannabis control policy, adolescents were more likely to ever use cannabis (odds ratio (OR) = 1.10, p = .001), use in past year (OR = 1.09, p = .007), and use regularly (OR = 1.26, p = .004). Although boys were substantially more likely to use cannabis, the correlation between cannabis liberalization and cannabis use was smaller in boys than in girls. With respect to detailed types of policies, depenalization was associated with higher odds of past-year use (OR = 1.14, p = .013) and regular use (OR = 1.23, p = .038), and partial prohibition was associated with higher odds of regular use (OR = 2.39, p = .016). The correlation between cannabis liberalization and regular use was only significant after the policy had been introduced for more than 5 years.ConclusionsCannabis liberalization with depenalization and partial prohibition policies was associated with higher levels of regular cannabis use among adolescents. The correlations were heterogeneous between genders and between short- and long-terms.

Highlights

Cannabis use, especially regular use, is associated with adverse health consequences including dependence symptoms, respiratory and cardiovascular diseases, impaired psychosocial development, psychotic outcomes, and traffic fatalities. [1,2,3,4] Cannabis remains the most commonly used illicit drug in the world, with estimated 125–203 million current users in 2009. [5] The prevalence is high among adolescents
Cannabis liberalization with depenalization and partial prohibition policies was associated with higher levels of regular cannabis use among adolescents
Health Behaviour in School-Aged Children Study (HBSC) data were used in this study

Summary

Introduction

Especially regular use, is associated with adverse health consequences including dependence symptoms, respiratory and cardiovascular diseases, impaired psychosocial development, psychotic outcomes, and traffic fatalities. [1,2,3,4] Cannabis remains the most commonly used illicit drug in the world, with estimated 125–203 million current users in 2009. [5] The prevalence is high among adolescents. From the late twentieth century, many countries had policy reforms to liberalize the traditional regime of criminal prohibition of cannabis. Some examples include Australia, Canada, Netherlands, United States, Uruguay, and many other countries in Europe While some jurisdictions such as Uruguay and Washington, Colorado in the United States regulated production and distribution very recently, [15,16] the liberalization reforms primarily focused on possession and use of small quantities of cannabis. Considering the heterogeneities in the presence of criminal sanctions, roles of judiciary and police, forms of penalties, levels of law enforcement, and target population, cannabis control regimes can be categorized into 4 types, including full prohibition, depenalization, decriminalization, and partial prohibition. Considering the heterogeneities in the presence of criminal sanctions, roles of judiciary and police, forms of penalties, levels of law enforcement, and target population, cannabis control regimes can be categorized into 4 types, including full prohibition, depenalization, decriminalization, and partial prohibition. [9,17] The latter 3 regimes represent existing forms of cannabis liberalization policies

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