Last month, the City of Miami Beach disclosed that they are considering changing the city ordinance around marijuana possession to allow for a fine rather than incarceration for possession of 20 grams or less of marijuana for personal use.  Although there was a time when this kind of policy change would have met with outrage and social protest, the changing climate towards marijuana use in the United States in the past several years makes this legislative consideration not all that surprising.  Although marijuana use is still illegal at the federal level, many state laws have been changed to allow for the medicinal use of marijuana or THC (the active ingredient in marijuana) under appropriate medical circumstances.  To date the following states have approved laws governing medical use of marijuana: California, Nevada, Arizona, New Mexico, Montana, Minnesota, Illinois, Michigan, New York, New Jersey, Maryland, Delaware, Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, Maine and the District of Columbia.  Additionally, Washington, Oregon, Colorado and Alaska have also legalized recreational use.

The significant change in the accessibility of marijuana with these legal changes have prompted the study of the impact of these changes on social perceptions, illegal marijuana use, prevalence of illicit drug use in youth and overall social impact.  The evidence-based research is still in its early stages and, as often is the case in early research, seems to be producing mixed results.  However, it does begin to shed light on the issues that could become problematic and the questions that need to be asked.

Medicinal Use vs. Recreational Use

Researchers are clear to point out whether they are reporting on medicinal use with controlled dosages versus recreational use.  The literature on medicinal use has produced promising evidence for the use of marijuana or THC compounds for the treatment of glaucoma, nausea and vomiting related to chemotherapy, AIDS-associated anorexia and wasting syndrome, chronic pain, inflammation, Multiple Sclerosis and Epilepsy.  In a brief review of the research in these areas, Volkow et al. (2014) present a balanced view suggesting that there is some evidence that cannabinoids (marijuana and other THC based compounds) could be a beneficial addition to treatment options for these medical conditions.

The social policy question has been raised as to whether the legalization of medicinal marijuana increases society’s comfort with the legalization of recreational marijuana use and what impact these changing social views will have on the prevalence of marijuana dependence in the overall population and, particularly, in youth.

Impact of Medicinal Marijuana Legalization on Recreational Juvenile Drug Use

It is widely accepted in the social psychology and health psychology literature that, as perception of risk decreases, the incidence and likelihood of a behavior occurring increases.  Based on this premise, researchers have questioned whether presenting marijuana as having medicinal benefit that outweighs its risk would reduce the overall risk perception of young adults and, consequently, increase recreational use.

Schuermeyer et al. (2014) examined the changes in marijuana attitudes and marijuana-use relate outcomes in Colorado following their policy changes and compared differences within-year between Colorado and non-medical marijuana states.  They reported finding a significant decrease in risk perception among all age groups between 2007-8 and 2010-11.  They also reported an increased incidence of past-year marijuana abuse/dependence in Colorado youth 12-17 years old.  This decreased risk perception and increased incidence of abuse/dependence was significantly different in Colorado from non-medical marijuana states.

Stolzenberg, D’Alessio & Dariano (2015) evaluated results from the National Survey on Drug Use and Health from 2002-2011 in two-year increments.  They reported that medicinal marijuana laws appear to increase recreational marijuana use in juveniles.  They proposed that the legalization of medicinal marijuana decreased social stigmatization of its use and reduced perceived risk of negative health outcome.  However, they also identified additional predictors of marijuana use at the state level, such as perceived availability, percent of juveniles skipping school, severity of perceived punishment for marijuana possession, alcohol consumption, percent of respondents with a father residing in household and percent of families in the state receiving public assistance.

With so many other predictive variables, it may be premature to conclude that medicinal marijuana legalization plays a significant role in the increase of recreational use in juveniles.  Additionally, there is a mounting body of research evidence that challenges this assumption.

Choo et al. (2014) examined the impact of state medical marijuana legislation on adolescent marijuana use using data from the Youth Risk Behavioral Surveillance Survey between 1991 and 2011.  In a sample of 11,703,100 students reporting across states and years, they did not find an overall increase in adolescent marijuana use related to the legalization of medical marijuana.  They cited additional studies by Harper et al. (2012) and Lynne-Landsman et al. (2013) as having similar findings when controlling for within state variables.  Choo et al. (2014) point out that adolescent substance use continues to be a significant public health issue with 42% of US adolescents reporting use of marijuana by 12^th grade.  However, they caution against drawing a causal relationship between the legalization of medical marijuana and the prevalence of juvenile marijuana use.

The Dangers of Low-Risk Perception

With some research pointing to lowering risk perception in relation to marijuana use, the question raised is – how bad is it really?

The answer is not absolute.  As in the medical conditions described above, sometimes controlled use of cannabinoids for the management of life-threatening and/or quality of life symptoms can have benefits that outweigh the risks.  In recreational use, THC use in any form can have negative legal implications in most states, as well as negative ramifications in the workforce (Phillips et al, 2015).  Smoking marijuana can have additional negative health repercussions when it comes to cancer risk and lung function (Volkow et al, 2014).  However, the clearest negative impact of uncontrolled, recreational long-term use of marijuana seems to be evident in adolescents.

Early onset marijuana use is associated with a significantly increased prevalence of addiction.  While 9% of those who experiment with marijuana will become addicted (Lopez-Quintero et al, 2011), the number increases to about 1 in 6 among those who start using marijuana as teenagers and to 25-50% among those who smoke daily (Hall & Degenhardt, 2009).  As compared to individuals who start using marijuana as adults, those who start in adolescence are approximately 2-4 times more likely to develop cannabis dependence within 2 years after first use (Chen, Storr & Anthony, 2009).

Adolescence is a particularly dangerous time for the introduction of environmental toxins to the brain, such as THC, because of the brain development that takes place until approximately age 21.  As compared to those who have had no exposure to THC, adults who smoked marijuana during adolescence have fewer neural connections in specific brain regions (Volkow et al, 2014).  Individuals who started using marijuana before the age of 17 have been found to have less cortical grey matter and larger white matter volumes on MRI and PET scans (Wilson et al, 2000).  Choo et al. (2014) review a number of studies that have demonstrated decreased memory, learning, attention and executive functioning in youth using marijuana that continues even several weeks after abstinence from use.  They also present findings that support permanent negative effects on cognition, links to schizophrenia and other psychotic disorders, respiratory problems, general malaise, neurocognitive problems, as well as social problems such as lower academic achievement, welfare dependence, unemployment, low relationship satisfaction, and low life satisfaction.

Conclusion

The research evidence appears to be clear that increases in adolescent marijuana exposure and use could lead to significant public health problems.  If lower risk perception increases the likelihood of increased marijuana use earlier in life, then it is imperative to understand factors that contribute to lower risk perception and increased use.

It may be too soon to determine whether policy changes and societal view changes will impact the prevalence rate of negative outcomes associated with marijuana dependence/abuse.  However, the research does seem to point to the importance of understanding the nuances of this issue, its implications in medicinal versus recreational versus abuse/dependence usage, and the assumptions that people make during times of societal view transitions.

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References

Chen, C., Storr, C., & Anthony, J. (2009). Early-onset drug use and risk for drug dependence problems. Addictive Behaviors, 34, 319-322.

Choo, E., Benz, M., Zaller, N., Warren, O., Rising, K., & Mcconnell, K. (2014). The Impact of State Medical Marijuana Legislation on Adolescent Marijuana Use. Journal of Adolescent Health, 55, 160-166.

Hall, W., & Degenhardt, L. (2009). Adverse health effects of non-medical cannabis use. The Lancet, 374, 1383-1391.

Harper, S., Strumpf, E., & Kaufman, J. (2012). Do Medical Marijuana Laws Increase Marijuana Use? Replication Study and Extension. Annals of Epidemiology, 2(22), 207-212.

Lopez-Quintero, C., Cobos, J., Hasin, D., Okuda, M., Wang, S., Grant, B., & Blanco, C. (2011). Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: Results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug and Alcohol Dependence, 115, 120-130.

Lynne-Landsman, S., Livingston, M., & Wagenaar, A. (2013). Effects of State Medical Marijuana Laws on Adolescent Marijuana Use. Am J Public Health American Journal of Public Health, 103, 1500-1506.

Phillips, J., Holland, M., Baldwin, D., Gifford-Meuleveld, L., Mueller, K., Perkison, B., . . . Dreger, M. (2015). Marijuana in the Workplace: Guidance for Occupational Health Professionals and Employers: Joint Guidance Statement of the American Association of Occupational Health Nurses and the American College of Occupational and Environmental Medicine. WORKPLACE HEALTH & SAFETY, 57(4).

Schuermeyer, J., Salomonsen-Sautel, S., Price, R., Thurstone, C., Min, S., & Sakai, J. (2014). Temporal trends in marijuana attitudes availability and use in colorado compared to non medical marijuana states: 2003-11. Drug and Alcohol Dependence, 140, 145-155.

Stolzenberg, L., D’Alessio, S., & Dariano, D. (2015). The Effect Of Medical Marijuana Laws On Juvenile Marijuana Use. International Journal of Drug Policy.

Volkow, N., Baler, R., Compton, W., & Weiss, S. (2014). Adverse Health Effects of Marijuana Use. New England Journal of Medicine N Engl J Med, 370(23), 2219-2227.

Wilson, W., Mathew, R., Turkington, T., Hawk, T., Coleman, R., & Provenzale, J. (2000). Brain Morphological Changes and Early Marijuana Use. Journal of Addictive Diseases, 19, 1-22.