Dataset Information

Impacts of Medical Marijuana Laws on Young Americans Across the Developmental Spectrum.

ABSTRACT: Introduction State legalization of marijuana for medical purposes could increase illicit marijuana use among young people. Medical marijuana laws may boost the availability of marijuana and reduce perceptions of its harmfulness, leading more young people to try it. Prior studies report little evidence that these laws are impacting marijuana consumption by young Americans, and none have systematically compared developmentally distinct age groups. Methods We performed multilevel, serial cross-sectional analyses on ten annual waves of U.S. National Survey on Drug Use and Health, from 2004 to 2013, comparing young people in states with and without medical marijuana laws. Disaggregated analyses compared multiple measures of marijuana use across approximately 450,300 individuals in early adolescence (12-14 years), late adolescence (15-17 years) and young adulthood (18-25 years). Results Dwelling in a state that had legalized medical marijuana was not associated with marijuana consumption in the past month among early adolescents, late adolescents or young adults. However, young adults living in medical marijuana states were significantly more likely to have initiated first use in the past year. Conclusions Medical marijuana laws increase the likelihood that young adults will start using marijuana but do not affect more vulnerable developmental groups in early and late adolescence. Delaying the age of first use into young adulthood can reduce the risk of a drug use disorder later in life. Young adults are in the peak years of engagement with illicit drugs and state medical marijuana laws appear to be leading larger numbers to try the drug.

SUBMITTER: Schmidt LA

PROVIDER: S-EPMC6440814 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Impacts of Medical Marijuana Laws on Young Americans Across the Developmental Spectrum.

Schmidt Laura A LA Jacobs Laurie M LM Vlahov David D Spetz Joanne J

Maternal and child health journal 20190401 4

Introduction State legalization of marijuana for medical purposes could increase illicit marijuana use among young people. Medical marijuana laws may boost the availability of marijuana and reduce perceptions of its harmfulness, leading more young people to try it. Prior studies report little evidence that these laws are impacting marijuana consumption by young Americans, and none have systematically compared developmentally distinct age groups. Methods We performed multilevel, serial cross-sect ...[more]

PMID: 30610531

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Project description:AimsMedical marijuana law (MML) enactment in the United States has been associated with increased cannabis use but lower traffic fatality rates. We assessed the possible association of MML and individual-level driving under the influence of cannabis (DUIC) and also under the influence of alcohol (DUIA).Design and settingThree cross-sectional U.S. adult surveys: The National Longitudinal Alcohol Epidemiologic Survey (NLAES; 1991-1992), the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; 2001-2002), and the NESARC-III (2012-2013).ParticipantsThe total n was 118 497: 41 764, 41 184, and 35 549 from NLAES, NESARC, and NESARC-III, respectively.MeasurementsAcross the three surveys, similar questions in the Alcohol Use Disorder and Associated Disabilities Interview Schedule assessed DUIC and DUIA. Ever-MML states enacted MML between 1991-1992 and 2012-2013 (overall period). Early-MML states enacted MML between 1991-1992 and 2001-2002 (early period). Late-MML states enacted MML between 2001-2002 and 2012-2013 (late period). MML effects on change in DUIC and DUIA prevalence were estimated using a difference-in-differences specification to compare changes in MML and other states.FindingsFrom 1991-1992 to 2012-2013, DUIC prevalence nearly doubled (from 1.02% to 1.92%), increasing more in states that enacted MML than other states (difference-in-differences [DiD] = 0.59%; 95% CI = 0.06%-1.12%). Most change in DUIC prevalence occurred between 2001-2002 and 2012-2013. DUIC prevalence increased more in states that enacted MML 2001-2002 to 2012-2013 than in never-MML states (DiD = 0.77%; 95% CI = -0.05%-1.59%), and in two early-MML states, California (DiD = 0.82; 95% CI = 0.06-1.59) and Colorado (DiD = 1.32; 95% CI = 0.11-2.53). In contrast, DUIA prevalence appeared unrelated to MML enactment.ConclusionsMedical marijuana law enactment in US states appears to have been associated with increased prevalence of driving under the influence of cannabis, but not alcohol.

Project description:AimsTo test, among US students: (1) whether perceived harmfulness of marijuana has changed over time, (2) whether perceived harmfulness of marijuana changed post-passage of state medical marijuana laws (MML) compared with pre-passage; and (3) whether perceived harmfulness of marijuana statistically mediates and/or modifies the relation between MML and marijuana use as a function of grade level.DesignCross-sectional nationally representative surveys of US students, conducted annually, 1991-2014, in the Monitoring the Future study.SettingSurveys conducted in schools in all coterminous states; 21 states passed MML between 1996 and 2014.ParticipantsThe sample included 1 134 734 adolescents in 8th, 10th and 12th grades.MeasurementsState passage of MML; perceived harmfulness of marijuana use (perceiving great or moderate risk to health from smoking marijuana occasionally versus slight or no risk); and marijuana use (prior 30 days). Data were analyzed using time-varying multi-level regression modeling.FindingsThe perceived harmfulness of marijuana has decreased significantly since 1991 (from an estimated 84.0% in 1991 to 53.8% in 2014, P < 0.01) and, across time, perceived harmfulness was lower in states that passed MML [odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.75-0.97]. In states with MML, perceived harmfulness of marijuana increased among 8th graders after MML passage (OR = 1.21, 95% CI = 1.08-1.36), while marijuana use decreased (OR = 0.81, 95% CI = 0.72-0.92). Results were null for other grades, and for all grades combined. Increases in perceived harmfulness among 8th graders after MML passage was associated with ~33% of the decrease in use. When adolescents were stratified by perceived harmfulness, use in 8th graders decreased to a greater extent among those who perceived marijuana as harmful.ConclusionsWhile perceived harmfulness of marijuana use appears to be decreasing nationally among adolescents in the United States, the passage of medical marijuana laws (MML) is associated with increases in perceived harmfulness among young adolescents and marijuana use has decreased among those who perceive marijuana to be harmful after passage of MML.

Project description:AimsTo conduct a systematic review and meta-analysis of studies in order to estimate the effect of US medical marijuana laws (MMLs) on past-month marijuana use prevalence among adolescents.MethodsA total of 2999 papers from 17 literature sources were screened systematically. Eleven studies, developed from four ongoing large national surveys, were meta-analyzed. Estimates of MML effects on any past-month marijuana use prevalence from included studies were obtained from comparisons of pre-post MML changes in MML states to changes in non-MML states over comparable time-periods. These estimates were standardized and entered into a meta-analysis model with fixed-effects for each study. Heterogeneity among the study estimates by national data survey was tested with an omnibus F-test. Estimates of effects on additional marijuana outcomes, of MML provisions (e.g. dispensaries) and among demographic subgroups were abstracted and summarized. Key methodological and modeling characteristics were also described. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed.ResultsNone of the 11 studies found significant estimates of pre-post MML changes compared with contemporaneous changes in non-MML states for marijuana use prevalence among adolescents. The meta-analysis yielded a non-significant pooled estimate (standardized mean difference) of -0.003 (95% confidence interval = -0.012, +0.007). Four studies compared MML with non-MML states on pre-MML differences and all found higher rates of past-month marijuana use in MML states pre-MML passage. Additional tests of specific MML provisions, of MML effects on additional marijuana outcomes and among subgroups generally yielded non-significant results, although limited heterogeneity may warrant further study.ConclusionsSynthesis of the current evidence does not support the hypothesis that US medical marijuana laws (MMLs) until 2014 have led to increases in adolescent marijuana use prevalence. Limited heterogeneity exists among estimates of effects of MMLs on other patterns of marijuana use, of effects within particular population subgroups and of effects of specific MML provisions.

Project description:ImportanceHistorical shifts are occurring in marijuana policy. The effect of legalizing marijuana for recreational use on rates of adolescent marijuana use is a topic of considerable debate.ObjectiveTo examine the association between the legalization of recreational marijuana use in Washington and Colorado in 2012 and the subsequent perceived harmfulness and use of marijuana by adolescents.Design, setting, and participantsWe used data of 253 902 students in eighth, 10th, and 12th grades from 2010 to 2015 from Monitoring the Future, a national, annual, cross-sectional survey of students in secondary schools in the contiguous United States. Difference-in-difference estimates compared changes in perceived harmfulness of marijuana use and in past-month marijuana use in Washington and Colorado prior to recreational marijuana legalization (2010-2012) with postlegalization (2013-2015) vs the contemporaneous trends in other states that did not legalize recreational marijuana use in this period.Main outcomes and measuresPerceived harmfulness of marijuana use (great or moderate risk to health from smoking marijuana occasionally) and marijuana use (past 30 days).ResultsOf the 253 902 participants, 120 590 of 245 065(49.2%) were male, and the mean (SD) age was 15.6 (1.7) years. In Washington, perceived harmfulness declined 14.2% and 16.1% among eighth and 10th graders, respectively, while marijuana use increased 2.0% and 4.1% from 2010-2012 to 2013-2015. In contrast, among states that did not legalize recreational marijuana use, perceived harmfulness decreased by 4.9% and 7.2% among eighth and 10th graders, respectively, and marijuana use decreased by 1.3% and 0.9% over the same period. Difference-in-difference estimates comparing Washington vs states that did not legalize recreational drug use indicated that these differences were significant for perceived harmfulness (eighth graders: % [SD], -9.3 [3.5]; P = .01; 10th graders: % [SD], -9.0 [3.8]; P = .02) and marijuana use (eighth graders: % [SD], 5.0 [1.9]; P = .03; 10th graders: % [SD], 3.2 [1.5]; P = .007). No significant differences were found in perceived harmfulness or marijuana use among 12th graders in Washington or for any of the 3 grades in Colorado.Conclusions and relevanceAmong eighth and 10th graders in Washington, perceived harmfulness of marijuana use decreased and marijuana use increased following legalization of recreational marijuana use. In contrast, Colorado did not exhibit any differential change in perceived harmfulness or past-month adolescent marijuana use following legalization. A cautious interpretation of the findings suggests investment in evidence-based adolescent substance use prevention programs in any additional states that may legalize recreational marijuana use.

Dataset Information

Impacts of Medical Marijuana Laws on Young Americans Across the Developmental Spectrum.

Publications

Impacts of Medical Marijuana Laws on Young Americans Across the Developmental Spectrum.

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