Daily marijuana use among college students is the highest it's been in more than three decades, and 51 percent of all full-time college students have admitted to smoking pot at some point in their lives.
The group of University of Michigan scientists who conduct the nationwide Monitoring the Future study says 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.
By 2013, that rate was up to 39 percent, meaning that 429 of the 1,100 students surveyed said they had used one or more drugs in the 12 months preceding the survey.
The study pointed out that 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," Lloyd Johnston, the principal investigator of the MTF study, said in a statement.
"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."
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.
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.
According to the study, 11 percent of college students in 2013 indicated some Adderall use without medical supervision in the prior 12 months.
The use of psycho-stimulants, including Adderall and Ritalin, has nearly doubled since the low point in 2008, but their illegal use remained steady between 2012 and 2013.
The next most frequently used illegal drugs by college students are ecstasy, hallucinogens and narcotic drugs other than heroin. About 5 percent of college students reported they had used one of these 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, the study showed.
Nearly 6 percent of students – 5.8 percent – said they had used ecstasy 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. Just over 2 percent admitted use in 2013.
Fewer than 1 percent of college students in 2013 admitted to using inhalants, crack cocaine, heroin, methamphetamine, "bath salts," GHB and ketamine in the previous 12 months.
Conversely, alcohol use has declined some on campuses in recent years. In 2008, 69 percent of students 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.
Overall, about three quarters – 76 percent – of college students indicated drinking at least once in the past 12 months, and 58 percent sad they had gotten drunk at least once in that period.