Marijuana use among US college students reaches new 35-year high

College students' use of marijuana in 2018 was at the highest level seen in the past three-and-a-half decades, according to the University of Michigan's annual national Monitoring the Future Panel study.

In addition, vaping of marijuana and of nicotine each doubled for college students between 2017 and 2018.

In 2018, 43% of full-time college students aged 19-22 reported using marijuana at least once in the prior 12 months (annual prevalence). The five-year trend, from 2013 to 2018, increased a statistically significant 7 percentage points. Twenty-five percent reported using at least once in the prior 30 days (30-day prevalence), showing a significant increase over the past five years. Both of these prevalence levels are at historic highs since 1983, when they were 45% and 26%, respectively.

Same-age high school graduates who are not full-time college students show a similar upward trend over time. In 2018, their annual prevalence was 43% and 30-day prevalence was 27%, the highest levels since the 1980s.

Thirty-day prevalence of vaping marijuana also increased for college students from 5.2% in 2017 to 10.9% in 2018, a significant 5.7 percentage point increase. Among noncollege respondents, 30-day prevalence was level at 8% in 2017 and 2018.

"This doubling in vaping marijuana among college students is one of the greatest one-year proportional increases we have seen among the multitude of substances we measure since the study began over 40 years ago," said John Schulenberg, principal investigator of the Monitoring the Future Panel Study.

Daily or near daily use of marijuana—defined as having used on 20 or more occasions in the prior 30 days—was at 5.8% in 2018 for college students. It has been between 4% and 6% in the past five years. Among same-age noncollege youth, it was 11.1%, nearly double the level for college youth. The gap between college and noncollege youth has widened in recent years.

"Daily marijuana use, especially among noncollege youth, is worrisome," said Schulenberg. "The brain is still growing in the early 20s, and as the Surgeon General just reported, the scientific evidence indicates that heavy marijuana use can be detrimental to cognitive functioning and mental health.

"Getting a foothold on the roles and responsibilities of adulthood may be all the more difficult for these 1-in-9 noncollege youth who use marijuana on a daily or near daily basis. As for college students, we know from our research and that of others that heavy marijuana use is associated with poor academic performance and dropping out of college."

There likely are multiple reasons for the continuing increase in marijuana use among college students and noncollege youth, according to the researchers. One possible reason is the ongoing decline in perceptions of risk of harm from regular marijuana use. In 2018, 22% of those aged 19-22 perceived regular use of marijuana as carrying great risk of harm, a significant 5 percentage point decline from 2017, and the lowest level since 1980 when tracking of this age group began.

"Perceptions of great risk peaked at 75% in 1991, when marijuana use among college and noncollege youth was at historic lows," said Lloyd Johnston, the original principal investigator of the Monitoring the Future study. "We have consistently seen this inverse relationship between perceptions of risks of harm and actual use, with changes in perceptions of risk typically preceding changes in use."

Vaping nicotine also showed dramatic increases for college students, with 30-day prevalence rising a significant 9.4 percentage points from 6.1% in 2017 to 15.5% in 2018, which again is one of the largest one-year proportional increases for any substance over the past 40 years. It increased nonsignificantly for noncollege respondents, from 7.9% in 2017 to 12.5% in 2018.

"2018 showed a rare occurrence, with nicotine use—in this case by vaping it—being higher among college than noncollege youth," Schulenberg said. "Typically, noncollege youth have much higher levels of nicotine use. For example, 30-day cigarette smoking in 2018 was 6.8% among college students and 17% among noncollege youth."

These findings come from the annual national Monitoring the Future Panel Study, which has been tracking substance use among American college students and noncollege youth since 1980. It is conducted by a team of research professors at the University of Michigan, funded by the National Institute on Drug Abuse. Results are based on data from college students one to four years beyond high school graduation enrolled full-time in a two- or four-year college in March of the given year, compared with same-age high school graduates not enrolled full-time in college.

This ongoing annual study also examined the use of other illicit drugs, alcohol, and tobacco. In 2018, use of most substances remained steady or declined modestly. Study results include:

• Annual use of any of the illicit drugs other than marijuana was 18% in 2018 for both college and noncollege youth. It has declined somewhat for both groups since recent highs in 2014.
• Two of the many illicit substances measured have shown recent increases among college students, though prevalence for both drugs remains relatively low. Annual cocaine use increased significantly over the past five years, from 2.7% in 2013 to 5.2% in 2018—the highest it has been over the past decade. For noncollege respondents, annual cocaine use has declined somewhat in the past few years to 4.2% in 2018. Annual prevalence of LSD has shown some uneven increases in the past few years for college students, rising to 4.1% in 2018, and for noncollege respondents, rising to 6.1% in 2018.
• The 2018 annual prevalence of nonmedical use of prescription narcotic drugs, such as OxyContin and Vicodin, showed a significant five-year decline for both college and noncollege youth, reaching the lowest levels reported since the late 1990s. Between 2013 and 2018, it dropped from 5.4% to 2.7% for college students and from 9.6% to 3.2% for noncollege respondents.
• The annual use of amphetamines continued to decline modestly for college students to 8.3% in 2018 and for noncollege respondents to 5.1 % in 2018. In contrast to what is true for most other illicit drugs, nonmedical amphetamine use has been higher among college students in recent years.
• Annual prevalence of MDMA (ecstasy and "Molly") has shown some uneven declines in recent years. In 2018, it was 4.3% for college students and 2.8% for noncollege respondents.
• Alcohol use has been declining for several years among college students, although it continues to remain their drug of choice. In 2018, binge drinking—defined as having five or more drinks in a row at least once in the past two weeks—significantly declined for college students to 28%, a record low since 1980. Binge drinking is more common among college males than females, and among college students than noncollege youth.
• Across 2012 through 2018 combined, 9.5% of college students reported high intensity drinking (10 or more drinks in a row in the past two weeks). Such use has declined somewhat over the past decade; it is more common among college men than women, and similar among college and noncollege youth. "There is good and bad news regarding alcohol use among college students. Alcohol use continues to decline, but excessive drinking clearly remains the major substance use problem on campuses," Schulenberg said. "Having 10 or more drinks in a row, which has been happening the past few years for 1-in-7 college men at least once per two-week period, can result in alcohol poisoning, serious injuries and a host of unwise decisions and dangerous behaviors that adversely affect them and those around them."
• In 2018, 30-day cigarette smoking among college students was 6.8%—a record low since 1980—consistent with the continuing decline over the past two decades. It is much higher among noncollege youth, although it has been declining for them as well, with 30-day cigarette use showing a significant decline to 17% in 2018.