5 Questions: Halpern-Felsher on teens’ misconceptions about marijuana

A survey of hundreds of California high-school students shows that teens don’t understand the risks of marijuana use, and are more likely to smoke it if they have seen marijuana ads.

- By Erin Digitale

Bonnie Halpern-

There’s a good news/bad news story playing out around teen smoking: After years of public health education about the dangers of cigarette use, teenagers’ cigarette smoking is declining. But their marijuana use hasn’t changed, with around 20 percent of 12th graders reporting that they recently smoked marijuana.

To find out why, Bonnie Halpern-Felsher, PhD, professor of adolescent medicine at the Stanford University School of Medicine, and her team recently conducted a survey of 786 students from 10 large high schools across California. They asked the teens about their beliefs regarding marijuana and their patterns of use. Science writer Erin Digitale asked Halpern-Felsher to describe the highlights of the study, which was recently published online in Preventive Medicine.

Q. You studied ninth and 12th graders’ perceptions of the risks of using marijuana, tobacco and blunts, which are marijuana rolled in a tobacco leaf. What did you find?

Halpern-Felsher: Our study revealed a number of important findings about how adolescents think about marijuana and blunts. Adolescents in this study were more likely to use marijuana and blunts than cigarettes. Further, they believed that more than half of their friends were using marijuana. The majority of marijuana and blunt users reported getting these from their friends, used them most often with friends and at friends’ houses, and often used marijuana or blunts when they were feeling stressed. Importantly, the adolescents who reported that their friends used marijuana were 27 percent more likely to use marijuana themselves. Compared with cigarettes, adolescents thought that marijuana and blunts were less likely to make them feel jittery or nervous, more likely to reduce stress and more likely to make them feel high or buzzed. Marijuana and blunts were also seen as less addictive, and perceived as easier to quit than cigarettes. Finally, more than half of the adolescents in the study reported seeing ads for the benefits of marijuana, and exposure to such ads was associated with a 6 percent greater chance of using marijuana.

Q. Were you surprised by any aspect of your findings?

Halpern-Felsher: While we expected adolescents to report more friends using marijuana than cigarettes, we were surprised by how strong the peer influence was on where and how adolescents use marijuana. We were also surprised that stress was the No. 1 reason for use. It was also surprising that the adolescents believed that about half of their close friends were using marijuana, while national data show that the actual rates are somewhere from 16 to 25 percent. We also didn’t realize how common it was for adolescents to see ads for the supposed benefits of marijuana, and how much such exposure to ads influenced their own use.

We weren’t surprised, but were concerned, that adolescents believe blunts are significantly less addictive than cigarettes. This was concerning because blunts contain nicotine, the drug that makes cigarettes and other tobacco products addictive.

Q. You saw that teens perceive marijuana as less risky than tobacco. How does that perception line up with evidence from studies of the two substances’ effects?

Halpern-Felsher: This is a complicated question, as much more research is needed. Some studies suggest that smoking marijuana has cardiovascular effects, including increased risk for heart attack. Studies also suggest that exposure to secondhand marijuana smoke impairs vascular endothelial function. Smoking a blunt confers additional risks, including nicotine addiction and cancer. More studies are needed to fully understand the effects of marijuana and blunts, but both products clearly entail significant risk.

Q. How do you think adults — parents, health educators, teachers, etc. — might help correct the inaccuracies in teens’ perceptions of marijuana?

Halpern-Felsher: Given that adolescents overestimated the extent to which their peers use marijuana, and that having friends who use marijuana was significantly related to the adolescents’ own use, dispelling misperceptions about peer use might be effective. Studies have shown that changing perceptions that substance use is a normative behavior results in lower overall use. This approach can be employed by teachers, health educators, parents and health-care providers.

As our other research has shown, adolescents receive little education or information about marijuana and blunts. For instance, they don’t understand that the tobacco leaves in which a blunt is rolled contain nicotine and many of the other harmful chemicals found in cigarettes. We need to explain to them that marijuana does confer risks, including likely risks to cardiovascular health and vascular function, and that marijuana is addictive, especially when used in the form of a blunt. We also need to explain that smoking any biomass can hurt your lungs.

Health messages also need to dispel the idea that marijuana is a way to reduce stress, and instead help adolescents find alternative stress-reducing strategies, such as exercise, healthy eating and so on.

Q. In the upcoming election, California voters are being asked to decide on Proposition 64, which, if passed, would legalize recreational marijuana use for adults 21 and older. What aspects of your findings might help voters make a decision about how to vote on this proposition?

Halpern-Felsher: Any legislation regarding marijuana should include education and regulation to let youth know about the real and potential harms of marijuana. [If it passes, some of the tax revenue that would be generated by Proposition 64 would be earmarked for drug education, prevention and treatment programs for youth.] Simply legalizing marijuana without education and regulation will likely increase social normalization of marijuana, leading youth to feel that marijuana is OK to use. Indeed, our findings that adolescents think marijuana use is socially acceptable and that such perceptions are related to use suggests that legalizing marijuana will only increase such perceptions. In addition to comprehensive marijuana education within the schools, parents and educators need to be better-informed so that they can talk to young people, and health-care providers need to assess and discuss marijuana use with their adolescent patients.

Also, voters may be interested to know that the American Academy of Pediatrics released a policy statement last year that favored decriminalizing marijuana possession but opposed legalizing recreational use. The AAP position, written by my Stanford colleague Seth Ammerman, MD, cited evidence that early marijuana use is associated with greater risk of addiction and greater potential harm to brain function. The AAP also expressed concerns that legalization would increase both teens’ access to marijuana and their exposure to marijuana marketing. Proposition 64 prohibits advertising marijuana directly to minors, but even with that caveat, teens will almost certainly see more marijuana advertising if the measure should pass. The connection we found between seeing marijuana ads and increased use lines up with the AAP’s concern.

About Stanford Medicine

Stanford Medicine is an integrated academic health system comprising the Stanford School of Medicine and adult and pediatric health care delivery systems. Together, they harness the full potential of biomedicine through collaborative research, education and clinical care for patients. For more information, please visit med.stanford.edu.

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