Are You in Love with Mary Jane?

Does the availability of medical marijuana increase the risk of recreational use among teens? Data suggest not.

Since 1996, when California became the first state in the US to pass a medical marijuana law (MML) and provided broad protection against prosecution for both physicians and patients, 17 other states and the District of Columbia have passed similar laws.  There have been arguments by opponents of MMLs that the passage of these laws could lead to increased non-medicinal use of marijuana by adolescents due to an increased ease of access.  Recent studies by Wall et al and Harper et al used data from the National Survey on Drug Use and Health to compare state-level prevalence of adolescent marijuana use from 2002-2008 for both states with and without MMLs.   Neither study found a significant increase in adolescent marijuana use before or after MMLs were enacted.   The authors of the current study expanded upon this research by analyzing data at the individual level.

This study utilized data collected from the Youth Risk Behavior Survey which polled adolescents 12-18 years old from 2003 to 2009 in four states: Montana (enacted MML in November 2004), Rhode Island (enacted MML in January 2006), Michigan (enacted MML in December 2008) and Delaware (enacted MML in May 2011).  The surveys were administered biennially with new samples for each wave of data collection.

The study evaluated self-reported adolescent lifetime marijuana use and past-month use.  Each state was evaluated before and after their individual MMLs were enacted and compared to a state that did not enact a MML within the same time period. Difference-in-difference analyses and linear probability models were used for data comparisons.  The study showed that only 2 out of 40 planned comparisons were statistically significant.  Montana had a statistically smaller decrease than Delaware in the probability of lifetime marijuana use between 2003 and 2009 (B=0.071, p=0.03) and also showed a statistically significant decrease in daily marijuana use compared to Delaware over the same period (B=-0.063, p=0.03).  All other comparisons were not statistically significant.

Commentary

Although this study had obvious limitations such as the unknown reliability of truthful self-reporting by survey respondents and evaluation of changes to medical marijuana laws (MMLs) after their initial passage, the data does not show an increase in non-medicinal adolescent marijuana use for states with MMLs.

Repealing these laws should not be expected to decrease adolescent use of marijuana. However, there should be more focus on continuing research and public awareness of possible long term adverse effects of marijuana on populations without a true medical need for its medicinal purposes.  Another argument continues: some believe that there would not be significant long term adverse effects of using marijuana. If so, can it also be argued that there should be legislative change to legally allow the use or possession of that currently illegal substance?  Legalization of marijuana might prevent another ill effect that many adolescents face; possession and use of marijuana are associated with both criminal charges and criminal history which ultimately increase a child’s chances for poverty and unemployment later in life. Would not poverty and lack of employment directly lead to adverse health?

Lynne-Landsman, SD, et al. AJPH. 2013; 103 (8): 1500-6.

by

Tyree Winters, DO