Elsevier

Journal of Health Economics

Volume 42, July 2015, Pages 64-80
Journal of Health Economics

The effect of medical marijuana laws on adolescent and adult use of marijuana, alcohol, and other substances,☆☆

https://doi.org/10.1016/j.jhealeco.2015.03.007Get rights and content

Highlights

  • We examine the medical marijuana laws (MMLs) in ten states between 2004 and 2012.

  • We estimate the policy effect on the use of marijuana, alcohol, and other substances.

  • MMLs increase marijuana use and binge drinking in adults aged 21 or above.

  • MMLs increase marijuana use initiation in adolescents and young adults aged 12–20.

  • MMLs have no discernible effect on underage drinking or other substance use.

Abstract

We estimate the effect of medical marijuana laws (MMLs) in ten states between 2004 and 2012 on adolescent and adult use of marijuana, alcohol, and other psychoactive substances. We find increases in the probability of current marijuana use, regular marijuana use and marijuana abuse/dependence among those aged 21 or above. We also find an increase in marijuana use initiation among those aged 12–20. For those aged 21 or above, MMLs further increase the frequency of binge drinking. MMLs have no discernible impact on drinking behavior for those aged 12–20, or the use of other psychoactive substances in either age group.

Section snippets

Medical marijuana law and potential risks and medical value of marijuana

In the last two decades, growing evidence has lent support to the efficacy and safety of marijuana as medical therapy to alleviate symptoms and treat diseases (see, for instance, Ben Amar, 2006, Campbell and Gowran, 2007, Krishnan et al., 2009, Pertwee, 2012, Gloss and Vickrey, 2012). This growing body of clinical evidence on marijuana's medicinal value has propelled many states toward a more tolerant legal approach to medical marijuana. In 1996, California signed the Compassionate Use Act into

Data sources

We pooled nine years of cross-sectional data from a restricted-access version of the National Survey on Drug Use and Health (NSDUH) 2004–2012 (CBHSQ, 2013). NSDUH is a nationally and state-representative10

Estimated effect of MML implementation on marijuana use

Fig. 1 shows an upward trend in past-month marijuana use rates among adults aged 21 or above in parallel with the implementation of MMLs. A relative increase in adult marijuana use in MML states emerges immediately after the laws take effect, and persists at least three years afterwards. Among adolescents and young adults aged 12–20, however, the corresponding trend in past-month marijuana use rates is not consistent. Bear in mind that the relative trends shown in Fig. 1 are equivalent to

Discussion

Three main pieces of evidence from our study inform the policy discussions of MMLs. First, we find a significant effect of MML implementation on increasing marijuana use. Estimates suggest that the populations responsive to MMLs are adolescents and young adults aged 12–20 who experimented with marijuana for the first time and adults aged 21 or above who tried marijuana prior to the introduction of the law. This latter group also has an increased risk of progression to almost daily/daily

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    The authors gratefully acknowledge the helpful comments on earlier drafts of this study from Sara J. Markowitz and David H. Howard. All errors are our own.

    ☆☆

    The authors declare that they have no relevant or material financial interests that relate to the research described in this study. The study was approved by the Emory University Institutional Review Board (IRB) through an expedited review procedure.

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