Addiction
Explore this journal >
Research Report

How does state marijuana policy affect US youth? Medical marijuana laws, marijuana use and perceived harmfulness: 1991–2014

Authors

  • Katherine M. Keyes,

    Corresponding author
    1. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
    2. Department of Psychiatry, Columbia University Medical Center, New York, NY, USA

    • Correspondence to: Katherine M. Keyes, Columbia University Department of Epidemiology, Mailman School of Public Health, 722 West 168th Street, Suite 503, New York, NY 10032, USA. E-mail: kmk2104@columbia.edu

    Search for more papers by this author

  • Melanie Wall,

    1. Department of Psychiatry, Columbia University Medical Center, New York, NY, USA
    2. New York State Psychiatric Institute, New York, NY, USA
    3. Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY, USA
    Search for more papers by this author

  • Magdalena Cerdá,

    1. Department of Emergency Medicine, School of Medicine, University of California, Davis, Sacramento, CA, USA
    Search for more papers by this author

  • John Schulenberg,

    1. Department of Psychology, University of Michigan, Ann Arbor, MI, USA
    2. Institute for Social Research, University of Michigan, Ann Arbor, MI, USA
    Search for more papers by this author

  • Patrick M. O'Malley,

    1. Institute for Social Research, University of Michigan, Ann Arbor, MI, USA
    Search for more papers by this author

  • Sandro Galea,

    1. School of Public Health, Boston University, Boston, MA, USA
    Search for more papers by this author

  • Tianshu Feng,

    1. Research Foundation of Mental Hygiene, New York, NY, USA
    Search for more papers by this author

  • Deborah S. Hasin

    1. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
    2. Department of Psychiatry, Columbia University Medical Center, New York, NY, USA
    3. New York State Psychiatric Institute, New York, NY, USA
    Search for more papers by this author

Abstract

Aims

To 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.

Design

Cross-sectional nationally representative surveys of US students, conducted annually, 1991–2014, in the Monitoring the Future study.

Setting

Surveys conducted in schools in all coterminous states; 21 states passed MML between 1996 and 2014.

Participants

The sample included 1 134 734 adolescents in 8th, 10th and 12th grades.

Measurements

State 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.

Findings

The 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.

Conclusions

While 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.

Continue reading full article

Ancillary

Article Information

DOI

10.1111/add.13523

Format Available

Full text: HTML | PDF

© 2016 Society for the Study of Addiction

Request Permissions

Keywords

  • Adolescents;
  • attitudes;
  • laws;
  • marijuana;
  • medical marijuana;
  • Monitoring the Future

Publication History

  • Issue online:
  • Version of record online:
  • Accepted manuscript online:
  • Manuscript Accepted:
  • Manuscript Revised:
  • Manuscript Received:

Supporting Information

Figure S1 US overall and state-specific estimates of the association between medical marijuana laws (MML) passage and marijuana use stratified by perceived harmfulness of marijuana.

Table S1 Years in which states were analyzed as passing medical marijuana laws (MML) laws and years in which state medical marijuana law implicitly permitted dispensing via care-givers and amounts per patient, or explicitly acknowledged dispensaries as either permitted or not declared illegal.

Table S2 Interactions between perceived harmfulness** of marijuana use and pre–post medical marijuana laws (MML) on MJ use, 1993*–2014.

Table S3 Association between medical marijuana laws (MML) passage and adolescent marijuana use, stratified by adolescent's perceptions of the perceived harmfulness of regular* marijuana use (1992–2014**).

Table S4 Association between medical marijuana laws (MML) passage and adolescent marijuana use, stratified by adolescent's perceptions of the perceived harmfulness* of marijuana, using an ordinal definition** of the number of occasions of marijuana use as the outcome.

Table S5 Association between medical marijuana laws (MML) with dispensary provision and adolescent marijuana use, stratified by adolescent's perceptions of the perceived harmfulness* of marijuana.

FilenameDescription
add13523-sup-0001-SI.docxWord 2007 document, 279KSupporting info item

Please note: Wiley-Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Related content

Articles related to the one you are viewing

Citing Literature

  • Number of times cited: 7
  1. 1Susan R.B. Weiss, Katia D. Howlett, Ruben D. Baler, Building smart cannabis policy from the science up, International Journal of Drug Policy, 2017, 42, 39CrossRef
  2. 2Christopher P. Salas-Wright, Michael G. Vaughn, Marijuana use among young people in an era of policy change: what does recent evidence tell us?, The American Journal of Drug and Alcohol Abuse, 2017, 43, 3, 231CrossRef
  3. 3Rosalie Liccardo Pacula, Rosanna Smart, Medical Marijuana and Marijuana Legalization, Annual Review of Clinical Psychology, 2017, 13, 1, 397CrossRef
  4. 4Katherine M. Keyes, Melanie Wall, Tianshu Feng, Magdalena Cerdá, Deborah S. Hasin, Race/ethnicity and marijuana use in the United States: Diminishing differences in the prevalence of use, 2006–2015, Drug and Alcohol Dependence, 2017, 179, 379CrossRef
  5. 5Christopher Cambron, Katarina Guttmannova, Charles B. Fleming, State and National Contexts in Evaluating Cannabis Laws, Journal of Drug Issues, 2017, 47, 1, 74CrossRef
  6. 6Alan J. Budney, Jacob T. Borodovsky, The potential impact of cannabis legalization on the development of cannabis use disorders, Preventive Medicine, 2017CrossRef
  7. 7Xinguang “Jim” Chen, Information Diffusion in the Evaluation of Medical Marijuana Laws’ Impact on Risk Perception and Use, American Journal of Public Health, 2016, 106, 12, e8CrossRef