16-Year Study: Medical Marijuana Laws Decrease Underage Use

Results of a large-scale, 16-year anonymized research project found that states with Medical Marijuana Laws (MMLs) and decriminalization statutes, underage cannabis consumption declines, especially among minority youth.

One concern some have regarding legalization of cannabis – whether for Medical (MMJ), or Adult Recreational Use (ARU) – is whether or not it will adversely affect youth. Specifically, a question often asked is, “will legalizing cannabis increase underage consumption?”

Lead Researcher Dr Rebekah Levine Coley said that, “Some people have argued that decriminalizing or legalizing medical marijuana could increase cannabis use amongst young people, either by making it easier for them to access, or by making it seem less harmful.”

“However, we saw the opposite effect,” said Dr Coley, and noted that results of the 16-year-long study show that in states where MMJ is legal, rates of underage consumption of cannabis have declined.

Those findings occurred even after accounting for other variables, including policies on tobacco and alcohol, economic trends, youth characteristics and state demographics.

Boston College researchers Rebekah Levine Coley, PhD; Summer Sherburne Hawkins, PhD, MS; Marco Ghiani, PhD; Claudia Kruzik, BA, and Christopher F. Baum, PhD, examined anonymous data from 861,082 adolescents aged 14 to 18+ years, 51% of whom were female, from 1999 to 2015 in state Youth Risk Behavior Surveys (YRBS), and found that in states with Medical Marijuana Laws, cannabis use by underage youth declined overall, and significant reductions in underage cannabis consumption by minority youth, specifically among Black and Hispanic youth, also occurred.

They found as well, that states’ marijuana decriminalization laws “predicted significant declines in marijuana use among 14-year olds and those of Hispanic and other ancestry.” Also, the consumption-lowering effects of MMLs “increased significantly with each year,” and that “neither policy was significantly associated with heavy marijuana use or the frequency of use.”

Dr Coley also said that, “after the enactment of medical marijuana laws, youths’ perceptions of the potential harm of marijuana use actually increased.”

The research also found that in states with ARU legislation, such laws had no noticeable effect upon adolescent cannabis use.

The study – “A quasi-experimental evaluation of marijuana policies and youth marijuana use” by lead researcher Rebekah Levine Coley, PhD, et al, was published online: 15 Feb 2019 – in the American Journal of Drug and Alcohol Abuse, and the full paper may also be downloaded either from that site as linked above, or this one here – A quasi-experimental evaluation of marijuana policies and youth marijuana use.