ANN ARBOR, Mich.—Marijuana use among American adolescents has increased gradually over the past two years (three years among 12th-graders) following years of declining use, according to the latest Monitoring the Future study, which has tracked drug use among U.S. teens since 1975.
"So far, we have not seen any dramatic rise in marijuana use, but the upward trending of the past two or three years stands in stark contrast to the steady decline that preceded it for nearly a decade," said University of Michigan researcher Lloyd Johnston, the study's principal investigator.
"Not only is use rising, but a key belief about the degree of risk associated with marijuana use has been in decline among young people even longer, and the degree to which teens disapprove of use of the drug has recently begun to decline. Changes in these beliefs and attitudes are often very influential in driving changes in use."
The proportion of young people using any illicit drug is also up slightly over the past two years. This measure is driven largely by marijuana use, because marijuana is the most widely used of all illicit drugs. In 2009, marijuana use in the prior 12 months (the annual prevalence rate) was reported by about 12 percent of the nation's 8th-graders, 27 percent of 10th-graders and a third of 12th-graders. The proportions saying they used any illicit drug in the past year are 15 percent, 29 percent and 37 percent, respectively.
The proportion of students reporting using any illicit drug other than marijuana has continued to decline for students in the 8th and 12th grades in 2009. The prevalence rates for using any such drug in the prior 12 months are 7 percent, 12 percent and 17 percent in grades 8, 10 and 12, respectively.
There were declines this year in the use of several specific drug classes. High school seniors showed significant drops in their use of LSD and other hallucinogens, continuing long-term gradual declines (use of these drugs had shown previous declines in the lower grades). There was some continuing decline in all grades in the use of cocaine (specifically, powder cocaine) with annual usage levels reaching the lowest levels since the early 1990s.
While use of ecstasy, inhalants and LSD is not rising currently, the investigators remain concerned because the perceived risk associated with those drugs has been dropping for several years and may leave young people open to renewed interest in those drugs.
The proportion of young people who see "great risk" associated with trying ecstasy has fallen appreciably and steadily since 2004 (2005, in the case of 12th-graders).
"Given the glamorous name and reputation of this drug, I could easily imagine it making a comeback as younger children entering their teens become increasingly unaware of its risks," Johnston said. "And, while LSD use is at historically low levels at present, the proportion of students seeing its use as dangerous has been in decline for a long time (although it did not decline further this year in two of the three grades), removing a major obstacle to experimentation. We have seen LSD make a comeback before. Clearly, it could happen again."
Likewise, 8th- and 10th-graders, who are most likely to inhale or "huff" gases and aerosols to get high, have shown a steady decline since 2001 in the belief that experimenting with inhalants is dangerous.
"This leaves them more vulnerable to any new stimulus toward trying inhalants," Johnston said.
While marijuana use is increasing and the use of several drugs continues to decline, the majority of illicit drugs covered in the study showed little further change this year, although most of them are at levels of use that are considerably below the recent peaks reached since the mid-1990s. These include ecstasy, crack cocaine, heroin, narcotics other than heroin, Vicodin (a narcotic analgesic), amphetamines, methamphetamine, crystal methamphetamine, tranquilizers, and three so-called "club drugs": Rohypnol, GHB and ketamine.
Prescription drugs have received considerable attention in the past couple of years as the Monitoring the Future study documented their rising rates of use. Fortunately, none (with the possible exceptions of Adderall and OxyContin) appears to be increasing at the moment.
After several years of decline, the use of amphetamines, outside of medical supervision, did not show any significant further decrease this year. However, the specific amphetamine, Ritalin, did show a further significant decline in annual prevalence among 12th-graders. That brought their annual prevalence of Ritalin use down to only 40 percent of what it was when its use was first measured in the study in 2001. Annual use fell from 5 percent to 2 percent of 12th-graders reporting any Ritalin use in the prior year that was not under a doctor's orders.
It would appear, though, that another prescription drug may be taking its place. Adderall, another stimulant used in the treatment of attention deficit hyperactivity disorder, was included in the survey for the first time this year. In 2009, it shows annual prevalence rates of use outside of medical supervision of 2 percent, 6 percent and 5 percent in grades 8, 10 and 12, respectively.
Sedative (barbiturate) use, which had risen considerably from 1992 through 2005, has fallen back a little since then, from an annual prevalence of 7 percent in 2004 to 5 percent in 2009 among 12th-graders (8th- and 10th-graders do not receive this question). Similarly, tranquilizer use, which grew considerably during the 1990s and peaked in 2002 (at an 8 percent annual prevalence rate among 12th-graders), has since fallen back a bit to 6 percent in 2009. Tranquilizer use has followed a similar trajectory at 10th grade, but 8th-grade use has not fallen back after rising. No further change was seen in 2009 for tranquilizer use at any of the three grades.
Narcotics other than heroin, taken as a class, have remained level, though at recent peak prevalence rates. Most of these drugs are opiate or opiate-type analgesics and include Vicodin and OxyContin. Vicodin use, while remaining at high levels, was essentially unchanged this year (with 3 percent, 8 percent and 10 percent of 8th-, 10th- and 12th-grade students, respectively, indicating use in the prior 12 months).
The picture for OxyContin is a little less clear. At all three grades, OxyContin use is higher today than it was when its use was first measured in 2002, although only 10th grade showed an increase in 2009 (+0.9 percentage points). The annual prevalence rates are now 2 percent, 5 percent and 5 percent, respectively, for OxyContin at the three grade levels. Whether this one-year increase at 10th grade is real or simply a sampling artifact will have to wait another year to be resolved. But the main point is that these two dangerous and highly addictive narcotic drugs remain at high levels of use among American teens.
Over-the-Counter Cough and Cold Medicines
The use of cough and cold medicines, like Robitussin, to get high showed no decline this year. These over-the-counter medications usually contain the active ingredient dextromethorphan. Annual prevalence rates have not changed much since 2006, when use of these drugs was first measured. The proportions of students surveyed in 2009 who say they have taken these drugs for the purpose of getting high in the prior 12 months are 4 percent, 6 percent and 6 percent in grades 8, 10 and 12, respectively.
"Despite the fact that they are sold over the counter, these drugs can be dangerous when consumed in the large quantities that young people tend to use in order to get high," Johnston said.
Salvia and Provigil
Two drugs were added to the 12th-grade questionnaires this year: salvia and Provigil.
Salvia, or salvia divinorum, is derived from a plant grown in the mountains of Mexico. It is an herb in the mint family that can induce relatively short-acting dissociative effects when chewed, smoked or taken as a tincture. The U.S. Drug Enforcement Administration has designated it a "drug of concern," but at present, it is not controlled under the federal Controlled Substances Act. The 2009 survey found that 6 percent of 12th-graders indicated having used salvia during the prior 12 months. Clearly this drug has begun to make inroads in the adolescent population.
The other drug added to the study in 2009 is Provigil (modafinil), which is a prescription-controlled medicine for improving wakefulness. It is usually prescribed to people experiencing excessive sleepiness as a result of sleep disorders due to sleep apnea, shift work or narcolepsy. The annual prevalence of using Provigil outside of medical supervision by 12th-graders in 2009 is 1.8 percent, suggesting that misuse of this drug by teens is not yet a serious problem.
Alcohol use has generally been in a long-term, gradual decline at all three grade levels, with 30-day (or past month) prevalence having fallen from recent peak levels by more than 40 percent among 8th-graders, by more than 25 percent among 10th-graders, and by about one-sixth among 12th-graders. For this year only, 8th-graders showed a continuation of the decline, while use in the upper grades leveled off.
Binge drinking, here defined as having five or more drinks in a row at least once in the prior two weeks, has shown similar proportional declines. Again, only 8th-graders showed any indication of the decline continuing this year. The rates in 2009 for having had any alcohol to drink in the past 30 days are 15 percent, 30 percent and 44 percent in 8th, 10th and 12th grade, respectively; while the two-week prevalence rates of binge drinking at least once in the prior two weeks are 8 percent, 18 percent and 25 percent.
Perceived risk for binge drinking continued to rise for 12th-graders but did not increase in the lower grades. When asked how easy it would be to get alcohol if they wanted some, the majority of students in all three grades said it would be "fairly easy" or "very easy," but such easy availability has declined considerably in recent years in the lower grades, particularly in 8th grade.
For example, in 1996, the proportion of 8th-graders saying it would be easy to get alcohol stood at its peak level of 75 percent, but by this year the statistic had fallen to 62 percent, including a significant decrease in 2009.
"It would appear that state and local efforts to crack down on sales to underage buyers, perhaps along with greater parental vigilance, have had an effect," Johnston said.
Teenage use of anabolic steroids increased in the late 1990s, reaching peak levels among 8th-graders in 2000, among 10th-graders in 2002 and among 12th-graders in 2004. Since those recent peaks, however, annual prevalence of steroid use has declined considerably, by about half in grade 8, by nearly two-thirds in grade 10 and by 40 percent in grade 12. In 2009, the proportions reporting any use of anabolic steroids in the past year were only 0.8 percent, 0.8 percent and 1.5 percent in grades 8, 10 and 12, respectively. Among boys, who have considerably higher use than girls, the rates were 1 percent, 1.2 percent and 2.5 percent, respectively.
Monitoring the Future has been funded under a series of competing, investigator-initiated research grants from the National Institute on Drug Abuse, one of the National Institutes of Health. In addition to Johnston, the lead investigators are Patrick O'Malley, Jerald Bachman and John Schulenberg, all research professors at the University of Michigan's Institute for Social Research. Surveys of nationally representative samples of American high school seniors were begun in 1975, making the class of 2009 the 35th such class surveyed. Surveys of 8th- and 10th-graders were added to the design in 1991, making the 2009 nationally representative samples the 19th such classes surveyed. The sample sizes in 2009 are 15,509 8th-graders in 145 schools; 16,320 10th-graders in 119 schools; and 14,268 12th-graders in 125 schools, for a total of 46,097 students in 389 secondary schools. The samples are drawn separately at each grade level to be representative of students in that grade in public and private secondary schools across the coterminous United States. Schools are selected with probability proportionate to their estimated class size.
The findings summarized here will be published in the forthcoming volume: Johnston, L. D., O'Malley, P. M., Bachman, J. G., & Schulenberg, J. E. (2010). Monitoring the Future national results on adolescent drug use: Overview of key findings, 2009 (NIH Publication No. [yet to be assigned]). Bethesda, MD: National Institute on Drug Abuse.