ANN ARBOR—More college students nationwide have added illicit drugs, such as marijuana and amphetamine, to their back-to-school supply lists.

Illicit drug use has been rising gradually among American college students since 2006, when 34 percent indicated that they used some illicit drug in the prior year; that rate was up to 39 percent by 2013. Most of this increase is attributable to a rising proportion using marijuana, according to the University of Michigan scientists who conduct the nationwide Monitoring the Future study.

Daily marijuana use is now at the highest rate among college students in more than three decades. Half (51 percent) of all full-time college students today have used an illicit drug at some time in their lives; roughly four in 10 (39 percent) have used one or more such drugs in just the 12 months preceding the survey.

The results are based on a nationally representative sample of some 1,100 students enrolled full time in a 2- or 4-year college in spring 2013. The survey is part of the long-term MTF study, which also tracks substance use among the nation’s secondary students and older adults under research grants from the National Institute on Drug Abuse.

Marijuana has remained the most widely used illicit drug over the 34 years that MTF has tracked substance use by college students, but the level of use has varied considerably over time. In 2006, 30 percent of the nation’s college students said they used marijuana in the prior 12 months, whereas in 2013 nearly 36 percent indicated doing so.

Of perhaps greater importance, daily or near-daily use of marijuana—defined as 20 or more occasions of use in the prior 30 days—has been on the rise. The recent low was 3.5 percent in 2007, but the rate had risen to 5.1 percent by 2013.

“This is the highest rate of daily use observed among college students since 1981—a third of a century ago,” said Lloyd Johnston, the principal investigator of the MTF study. “In other words, one in every 20 college students was smoking pot on a daily or near-daily basis in 2013, including one in every 11 males and one in every 34 females. To put this into a longer-term perspective, from 1990 to 1994, fewer than one in 50 college students used marijuana that frequently.”

Nonmedical use of the amphetamine Adderall, used by some students to stay awake and concentrate when preparing for tests or trying to finish homework, ranks second among the illicit drugs being used in college. Eleven percent of college students in 2013—or one in every nine—indicated some Adderall use without medical supervision in the prior 12 months.

The use of psychostimulants, including Adderall and Ritalin, has nearly doubled since the low point in 2008, though there was no further increase in this measure between 2012 and 2013.

The next most frequently used illicit drugs by college students are ecstasy, hallucinogens and narcotic drugs other than heroin, with each of these three having about 5 percent of college students reporting any use in the prior 12 months.

Ecstasy use, after declining considerably between 2002 and 2007, from 9.2 percent annual prevalence to 2.2 percent, has made somewhat of a comeback on campus. It rose to 5.8 percent using in the prior 12 months in 2012, and was at 5.3 percent in 2013. Hallucinogen use among college students has remained at about 5 percent since 2007, following an earlier period of decline.

The use of narcotic drugs other than heroin, like Vicodin and OxyContin, peaked in 2006, with 8.8 percent of college students indicating any past-year use without medical supervision. Past-year use of these dangerous drugs by college students has since declined to 5.4 percent in 2012, where it remained in 2013.

Use of synthetic marijuana, which used to be legally available and was sold over-the-counter in convenience stores and other shops, ranked fairly high in 2011 with past-year use at more than 7 percent of college students that year. Use has fallen sharply in the two years since, however, to just over 2 percent in 2013 (secondary school students have shown a similar recent drop in their use of synthetic marijuana, according to the Monitoring the Future annual surveys of middle and high school students).

The use of salvia, an herb in the mint family, has fallen sharply since 2009, when it was first added to the study, from 5.8 percent of college students reporting use in the prior 12 months to just 1 percent in 2013.

Other use of illicit drugs on the decline
The use of some other illicit drugs by college students also has declined in the past decade, including crack cocaine, powder cocaine, tranquilizers and hallucinogens other than LSD (which involves psilocybin, e.g., “magic mushrooms”).

Another encouraging result is that a number of illicit drugs have been used in the prior 12 months by fewer than 1 percent of college students in 2013. These drugs include inhalants, crack cocaine, heroin, methamphetamine, “bath salts,” GHB and ketamine.

In general, female college students (who are now in the majority) are less likely to use these drugs than are their male counterparts. For example, 40 percent of college males used marijuana in the past year compared to 33 percent of college females. Also, 24 percent of males versus 16 percent of females used some illicit drug other than marijuana. Daily or near-daily use of marijuana was particularly concentrated among college males, with nearly 9 percent of them indicating marijuana use on 20 or more occasions in the prior 30 days, compared with only 3 percent of college females.

Mixed results found in alcohol use
There remains plenty of alcohol use on the nation’s college campuses, with about three quarters (76 percent) of college students indicating drinking at least once in the past 12 months and more than half (58 percent) saying they had gotten drunk at least once in that period.

In fact, more than a third (35 percent) said they had consumed five or more drinks on at least one occasion during the two weeks just prior to the survey. Particularly worrisome are rates of what the investigators call “extreme binge drinking.” Averaged across years 2005 to 2013, they find that one in eight (13 percent) college students had 10+ drinks and one in 20 (5 percent) had 15+ drinks in a row in the past two weeks.

Despite these high rates of involvement, alcohol use has declined some on campus in recent years. In 2008, 69 percent said they had at least one drink in the prior 30 days, whereas in 2013 that number had dropped to 63 percent. Similarly, the percent indicating that they got drunk during that period fell from a recent high of 48 percent in 2006 to 40 percent by 2011, where it then remained through 2013.

To some degree these declines may reflect the declines observed among high school seniors before they even went off to college, since MTF finds that drinking rates have been declining and are at historic lows among high school students.

The age peers of college students—that is, young adults who are also one to four years out of high school but are not full-time college students—have roughly equivalent proportions to college students in their past-year use of any illicit drug or any illicit drug other than marijuana.

They also have quite similar rates of several specific drugs, including past-year use of marijuana, ecstasy, hallucinogens other than LSD, and extreme binge drinking. However, they are twice as likely as college students to be daily marijuana users, and they have annual prevalence rates of use for several particularly dangerous drugs that are roughly two to three times as high as rates found among college students. These include crack cocaine, crystal methamphetamine, heroin and narcotic drugs other than heroin (including OxyContin and Vicodin, specifically). The noncollege segment also has a daily cigarette smoking rate roughly three times what it is among college students, but they have a somewhat lower rate of having been drunk in the prior 30 days (34 percent) than do college students (40 percent).

Johnston, L. D., O’Malley, P. M., Bachman, J. G., Schulenberg, J. E. & Miech, R. A. (2014). Monitoring the Future national survey results on drug use, 1975–2013: Volume 2, College students and adults ages 19–55. Ann Arbor: Institute for Social Research, The University of Michigan, 424 pp. Available at: http://monitoringthefuture.org/pubs/monographs/mtf-vol2_2013.pdf

The Monitoring the Future study is now in its 40th year and has surveyed nationally representative samples of full-time college students one to four years beyond high school each year for 34 years, starting in 1980. The annual samples of college students have ranged between 1,100 and 1,500 per year.

MTF is an investigator-initiated research undertaking, conceived and conducted by a group of research professors at the University of Michigan’s Institute for Social Research (listed as authors below) and funded under a series of competitive research grants from the National Institute on Drug Abuse, one of the National Institutes of Health.

MTF also conducts a national survey of high school seniors each year, and a random subsample of those 12th graders is drawn for follow-up by mail in future years. Those who are found to be in college full-time one to four years past high school comprise the college student sample. They are not drawn from particular colleges or universities, which helps to make the samples more representative of the wide range of institutions offering a college degree.

The findings are drawn from chapters 8 and 9 in the newly published monograph “Monitoring the Future national survey results on drug use, 1975–2013: Volume 2, College students and adults ages 19–55”: http://bit.ly/1o6oqkS.