Longitudinal Effects of School Drug Policies on Student Marijuana Use in Washington State and Victoria, Australia

摘要

Objectives. We examined the longitudinal effect of schools’ drug policies on student marijuana use. Methods. We used data from the International Youth Development Study, which surveyed state-representative samples of students from Victoria, Australia, and Washington State. In wave 1 (2002), students in grades 7 and 9 (n?=?3264) and a school administrator from each participating school (n?=?188) reported on school drug policies. In wave 2 (2003), students reported on their marijuana use. We assessed associations between student-reported and administrator-reported policy and student self-reported marijuana use 1 year later. Results. Likelihood of student marijuana use was higher in schools in which administrators reported using out-of-school suspension and students reported low policy enforcement. Student marijuana use was less likely where students reported receiving abstinence messages at school and students violating school policy were counseled about the dangers of marijuana use. Conclusions. Schools may reduce student marijuana use by delivering abstinence messages, enforcing nonuse policies, and adopting a remedial approach to policy violations rather than use of suspensions. Marijuana is the most widely used illicit drug worldwide, 1,2 with an estimated 181 million (3.9%) of the world’s adults using it in 2011. 3 Surveys in the United States and Australia have shown that marijuana use is particularly high among adolescents. 4,5 Concern about marijuana use has increased in recent years as a result of improved understanding of the harmful health and psychological effects of frequent use, especially among adolescents and young adults. 6,7 At the same time, many US states have passed marijuana laws making it legal for adults older than 21 years to possess small amounts of marijuana for medical purposes. Two states—Colorado and Washington—have legalized marijuana for recreational use by adults. Studies on the impact of marijuana legislation on marijuana use by US adolescents have yielded mixed results, with some pointing to an increase in use and others to no change or to a decrease in marijuana use. 8–13 Marijuana use is illegal in Australia. 14 School-based prevention programs and policies have become the dominant mode of drug prevention for adolescents. 15 School drug policies aim to reduce levels of adolescent substance use by restricting access to drugs and exposure to drug use during school hours. Studies measuring access to marijuana at the individual, school, and country levels have shown consistent associations between increased access and higher rates of self-reported use by adolescents. 16–18 An Australian study showed that high rates of school-level marijuana use (an indirect measure of exposure) are associated with increased risk of use by secondary students. 19 In addition, students in Swiss schools with more incidents of marijuana intoxication (as reported by teachers) were more likely to report marijuana use, regardless of peer use, 20,21 itself a salient risk factor. 19,22 Even in the absence of direct exposure to others’ marijuana use, students may be influenced by the general level of acceptability or disapproval of marijuana use in the broader school environment. 23,24 Thus, school drug policy may have a further potentially important function in addressing marijuana social norms in the school context. Although almost all secondary schools in the United States and Australia have illicit drug policies, school-to-school variation in policy content exists. 25–27 Schools differ in how they develop, communicate, and enforce their policies as well as in policy intent (e.g., goals of abstinence vs harm minimization). In addition, schools vary with respect to their responses to incidents of student drug use, which range from highly punitive approaches such as expulsion and suspension to remedial responses such as counseling. 25–27 Despite calls from leading government agencies for schools to implement evidence-based, whole-school drug education policies and programs, 28,29 empirical evidence of effective policy effects is relatively scarce. Studies examining the effectiveness of school drug policies in reducing student drug use have demonstrated mixed results, although there is some evidence of the importance of policy enforcement. 30 The majority of studies have focused on the impact of tobacco policy on student smoking. 31–42 Fewer studies have investigated the impact of policies on student alcohol 43–46 and illicit drug use. 47,48 With 1 exception, 45 none of these studies has demonstrated a longitudinal relationship between school policy and subsequent drug use. Further research is required to understand how these policies affect student drug use. Particularly needed are studies addressing the predictive impact of various elements of school policy, including punitive versus remedial policies and responses, policy enforcement, and exposure to abstinence and harm minimization messages related