For opponents of increasingly relaxed marijuana laws across the US over the past 2 decades, a primary concern has been the possibility that the trend could lead to higher rates of use among adolescents. It has been proposed that they could be directly influenced by having easier access to the drug via adults who can legally buy it and then pass it on to adolescents, and indirect effects may arise from a reduced perception of marijuana as risky and socially unacceptable. New findings published in the Journal of the American Academy of Child and Adolescent Psychiatry, however, indicate that those fears are unfounded thus far.
While previous data show that rates of use in this age group have remained relatively stable, the current study is the first to explore adolescents’ rates of marijuana use disorders. “The distinction between experimental use and abuse or dependence is important because there may be many individual-level factors that confer liability to problem use among adolescent marijuana users,” the authors wrote. To that end, they further explored variables that may attenuate any noted trends.
Researchers at Washington University School of Medicine in St. Louis and Eastern Virginia Medical School in Norfolk investigated trends in marijuana use disorders and potential explanatory factors among 216,852 US adolescents aged 12 to 17 years who are part of the ongoing National Survey on Drug Use and Health. The authors inquired about past-year use among participants who had reported ever using marijuana, and those who reported 6 or more days of use in the previous year were assessed for past-year abuse and dependence per DSM-IV criteria.
From 2002 to 2013, there was a 9.85% reduction in the overall prevalence of use, or a decrease of 0.9% per year (odds ratio [OR] = 0.989 per year; 95% CI ¼ 0.984, 0.994; P < .001). The past-year prevalence of marijuana use disorders in the sample decreased by 24% during the period examined, and the trend was attenuated by a reduction in the rate of conduct problems such as fighting and stealing. The analysis indicates that “the reduction in the prevalence of marijuana use disorders is specific to adolescents with conduct problems… that there has been a decline in the prevalence of marijuana use disorders with comorbid conduct problems,” but negligible change in prevalence among those without conduct problems, according to the paper.
There is a growing recognition of a shared etiology between substance use disorders and conduct problems in childhood, which could both stem from a tendency toward externalizing behaviors. The new results indicate there may be an as-yet-unidentified environmental factor influencing the observed reduction in both marijuana use disorders and behavioral problems. “Identification of such factors would facilitate more effective prevention strategies for marijuana problems and other aspects of behavioral health,” the authors concluded.
During the study period, 13 states passed medical marijuana legislation while 10 states eased legal consequences of adult use. The concurrent reduction in rates of use and abuse among adolescents implies that that related concerns about increased use in this demographic group have not materialized.
Grucza RA, Agrawal A, Krauss MJ, et al. Declining prevalence of marijuana use disorders among adolescents in the United States, 2002 to 2013. J Am Acad Child Adolesc Psychiatry. 2016;55:487-494.e6.