Medical marijuana-Dr. Plunk's study

A study led by Andrew Plunk, PhD, Assistant Professor of Pediatrics at EVMS, and published today in the journal Drug and Alcohol Dependence, documents the first evidence that medical marijuana laws have a long-term negative impact on educational attainment. 

In states with medical marijuana laws, the study found a 10 percent increase in high-school dropout among 12th-graders. Teens living in those states who did complete high school were less likely either to enroll in college or to complete a college degree, the study also reports. 

The study used several large datasets, such as the U.S. Census. People all across the U.S. were compared based on whether they lived in a state with a medical marijuana law when they were high-school age between the years 1994 and 2013. 

“We’ve known for a long time that teens who use marijuana tend to have higher rates of high-school dropout,” Dr. Plunk says. “But there’s been some disagreement over whether marijuana causes lower educational attainment. One implication of our study is that there likely is a direct link between marijuana and education. And while we need to do more work to verify exactly how medical marijuana laws, and by extension marijuana use, directly affect educational attainment, these findings are an important first step.” 

The study implies that legalizing medical marijuana could be associated with an additional 120,000 high school dropouts over a 17-year span. It also found that the laws were associated with a 62 percent increase in daily marijuana use among 12th-graders. “These results especially underscore the importance of ensuring that medical marijuana intended for adults doesn’t end up diverted to youth,” Dr. Plunk says. 

Also, the laws’ impact doesn’t seem to be limited to high school. “Living in a state with medical marijuana as a 14- to 18-year-old,” Dr. Plunk explains, “could have had a long-term impact on how someone uses the drug as a young adult. Our study suggests that the passage of medical marijuana laws could have led to 5.9 percent fewer high school graduates going on to college. And of those students who began college, these laws also could have led to 1.9 percent fewer of them completing a college degree. This represents an enormous unintended consequence for America’s youth.” 

The study, “The Impact of Adolescent Exposure to Medical Marijuana Laws on High School Completion, College Enrollment and College Degree Completion,” can be read here

Dr. Plunk notes that these findings should be interpreted cautiously until other studies can verify them. “We still need to better understand how exposure to medical marijuana laws in high school might affect marijuana use and educational attainment years later,” he says. “We’re confident that medical marijuana laws had some impact on young people, but we need to know more about how that happened, especially for college enrollment and degree completion.” 

Dr. Plunk and his co-authors, which include EVMS colleagues Paul Harrell, PhD, Assistant Professor of Pediatrics, and Kelli England Will, PhD, Professor of Pediatrics, urge the nation’s legislators, educators and parents to remember the lessons learned from alcohol and tobacco. 

“There are legitimate reasons to allow medical marijuana,” Dr. Plunk says, “and our study also doesn’t speak to an issue like decriminalization. But changes in drug policy do signal changes in our attitudes about drug use. We need to remember that marijuana is still a drug of potential misuse. This is especially important for young people, since the developing brain is likely more sensitive to the negative consequences of drug use.” 

The peer-reviewed journal Drug and Alcohol Dependence is devoted to publishing original research, scholarly reviews, commentaries and policy analyses in the areas of drug, alcohol and tobacco use and dependence. 

This study was supported by the National Institute on Drug Abuse of the National Institutes of Health under award numbers R01DA031288 and K02DA032573. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.