This is Archived Content

This content is available for historical purposes only. It may not reflect the current state of science or language from the National Institute on Drug Abuse (NIDA). View current testimonies on

February 19, 2013
NIDA Director, Dr. Nora D. Volkow

We know from abundant research that marijuana use during adolescence has the potential to set young people up for a cascade of life-altering events, impeding their success and hindering them from fulfilling their potential. Yet this reality is increasingly lost on teenagers. The annual Monitoring the Future (MTF) survey of drug use and attitudes has for several years shown a steady drop in the number of middle- and high-school students who think occasional or even regular marijuana users risk harming themselves physically or in other ways. This declining perception of risk parallels increased use. One in 15 high-school seniors now use marijuana daily. In fact, while most drug and alcohol use continues to decline or hold steady, marijuana is almost the only licit or illicit drug showing significant five-year increases in the MTF survey.

Young people’s growing skepticism about marijuana’s dangers is reflected in the questions I and other NIDA scientists receive from high school students every winter during our National Drug Facts Chat Day. This year’s Chat Day—the biggest ever—was on January 31, and we received hundreds of questions about marijuana. Many of these students challenged our claims about the dangers of this drug, expressing their belief that it is safer than other drugs, that it is not actually addictive, or that it is even beneficial. Some teens are no doubt hearing and being influenced by marijuana’s many outspoken advocates, who claim that the drug does not deserve continued Schedule I status and that decades of prevention messaging have overstated its dangers. The ongoing public conversation over medical marijuana may contribute to the impression that, since some people use marijuana therapeutically, it couldn’t be that harmful.

But given that now nearly half of teens try marijuana before they graduate, some of their skepticism about the drug’s dangers could also be based on their own direct personal experiences, or that of their friends. If a young person smokes marijuana once or twice and suffers no apparent ill effects, it might be natural to conclude that NIDA and other authorities are wrong—or at least stretching the truth—about the risks they face in using it.

The consequences of marijuana use indeed are somewhat different than those of other drugs, and they are likely to be less apparent to a casual teen user. Users of marijuana by itself are unlikely to risk a life-threatening overdose, for instance, and there is even some doubt as to whether it is as harmful to the lungs as tobacco (the jury is still out on lung cancer). Rather, marijuana use, particularly when initiated at a young age, sets the user on a downward life trajectory, one that is driven by a constellation of factors that include altered cognitive and social development. (I’ve discussed some of the recent evidence for this in previous messages.) Unfortunately, cognitive ability that declines over a span of months or years (as well as other, long-term effects on life and well-being) may not be the kind of harm that young people are easily able to perceive.

Given the increases we are seeing in marijuana use among this age group, it is more crucial than ever to challenge the impression many of them have that marijuana is a benign, unfairly demonized substance. We must also do more to counter their dangerous misconception that marijuana is not addictive. Research suggests that about 9 percent of all users become addicted and that, among those who start young, the percentage is closer to 17 percent—or one in six. A quarter to a half of those who use marijuana daily are addicted to the drug. Thus many of the nearly 7 percent of high-school seniors who say they smoke marijuana on a daily or near-daily basis are already addicted or are well on their way—besides functioning at a sub-optimal level all of the time.

We clearly face an uphill battle getting this message across. With recreational marijuana use recently legalized in two states and increasing public pressure to ease restrictions on the drug nationwide, the availability of this drug is bound to increase. Only time will tell how these factors influence teens’ perception of marijuana’s safety or lack thereof. The key may be to do a better job of educating America’s youth about the value of their brains, and how utterly important it is not to engage in behaviors that could permanently compromise that organ during a very vulnerable period in its development.