Daily Marijuana Use in Teens Highest Since the 1970s

Increase May Reflect 'Softening' of Attitudes Among Young People That Marijuana Is Not Harmful

Caroline Cassels

December 15, 2010

December 15, 2010 — A significant increase in marijuana use among US youth, especially in preteens, including a jump in daily use, are among the key findings from the 2010 Monitoring the Future Survey (MTF) annual national survey released by the National Institute on Drug Abuse (NIDA).

Led by Lloyd Johnston, PhD, investigators from the University of Michigan, Ann Arbor, found a declining trend in overall marijuana use among teens in grades 8, 10, and 12 appears to be reversing itself. This finding corresponds to a trend showing that the percentage of teens who perceive marijuana use as harmful is declining.

Dr. Nora Volkow

In 2010 overall marijuana use rates were 6.1% of high school seniors, 3.3% of 10th graders, and 1.2% of 8th graders compared with 2009 rates of 5.2%, 2.8%, and 1.0%, respectively.

Daily use increased in all 3 grades, including a significant increase from 6.5% in 2009 to 8% in 2010 among 8th graders.

"These increases in daily marijuana use are actually quite large — more than 10% — and are particularly relevant because daily use of marijuana is likely to result in more adverse effects than more infrequent use," NIDA Director Nora Volkow, MD, told reporters attending a press briefing where the survey results were released.

The survey showed that most measures of marijuana use, including daily, monthly, and exposure to marijuana during a 1-year period, increased among 8th graders, and daily marijuana use increased significantly among all 3 grades.

Young People Most Vulnerable

"Young people are particularly vulnerable to the adverse effects of drugs, and we know from epidemiological studies, as well as studies in laboratory animals, that the younger the age of initiation, the greater likelihood that they will be dependent," said Dr. Volkow.

"In clinical studies, epidemiology has shown that those who are exposed to marijuana at age 17 are more likely not just to become dependent on marijuana but are more likely to become dependent on a wide variety of drugs," she added.

Dr. Volkow also pointed out that although there is still debate about the potential long-term impact of marijuana on the brain, there is no doubt that it has an adverse effect on memory and learning ability.

According to Dr. Johnston, in the 1970s 1 in every 11 high school seniors was a daily pot user. Today, he noted this rate is 1 in 16. "We're not as bad as we were, but the trend is still going in the wrong direction," he said.

According to the survey, which included 46,482 students from 396 private and public schools across the United States, at 21.1% rates of marijuana use among 12th graders now top cigarette smoking rates of 19.2% in this group.

Perhaps not surprisingly, researchers note that increases in marijuana use correlate with a "softening" of attitudes among young people about the perceived harm of the drug.

"The proportion of kids who view marijuana use as dangerous has been declining in recent years, including this year, and that usually is a predictor of what is going to happen to use in coming years," said Dr. Johnston.

Significant Changes in Ecstasy Use

The survey also revealed a significant increase in the reported use of MDMA (Ecstasy), with 2.4% of 8th graders citing past-year use compared with 1.3% in 2009. Similarly, past-year MDMA use among 10th graders increased from 3.7% to 4.7% in 2010.

According to Dr. Johnston, Ecstasy use "took off" in the late 1990s, peaking in 2001 and then plummeted for 3 or 4 years as young people began to see it as much more dangerous than their predecessors.

Unfortunately, said Dr. Johnston, perceived risk for ecstasy has been declining since about 2004, and as a result younger students are not as aware as older students of the drug's risk — a phenomenon Dr. Johnston described as "generational forgetting."

With Ecstasy, we have not only seen an end to the decline but the start of an increase in use, and that is bad news for everybody. It is not large enough to be statistically significant, but we think it is real. There is still a small decline among 12th graders, which is good news, but we think that will be over in a year or 2.

Also of concern, said Dr. Johnston, is that the downward trend in cigarette smoking appears to have stalled in all 3 grades studied. Greater marketing of other forms of tobacco — including use of small cigars and hookahs — prompted investigators to add these measures to the 2010 survey. They found that among 12th graders 23.1% used small cigars and 17.1% used hookahs.

It has been wonderful news that smoking among teens has been decreasing in large proportions. However, this wonderful decline is now over among younger teens, where we've seen not only an end to the decline but an increase," said Dr. Johnston.

Abuse of prescription drugs and over-the-counter medications continues to be a problem and after marijuana accounts for the largest proportion of drug abuse among 12th graders.

The survey results showed that among 12th graders, past-year nonmedical use of Vicodin decreased from 9.7% to 8%. However, past-year nonmedical use of OxyContin remains unchanged across the 3 grades and has increased in 10th graders during the past 5 years.

In addition, past-year nonmedical use of the stimulant medication Adderall and over-the-counter cough and cold medicines among 12 graders remains high at 6.5% and 6.6%, respectively.

The survey also revealed that alcohol use — including binge drinking — is declining. Among high school seniors, 23.2% report having 5 or more drinks in a row during the past 2 weeks, down from 25.2% in 2009 and from the peak of 31.5% in 1998.

In 2010 all 3 grades showed further decline in both measures — drinking and binge drinking — and these are significant for all the grades combined. So the net effect is that today we have the lowest proportion of young people drinking in the history of the [MTF survey]," said Dr. Johnston.

The study authors have disclosed no relevant financial relationships.

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