Marijuana use by college students has spiked in the last decade, a new survey shows.
Monitoring the Future (MTF), a continuing study of American youth, reports that nearly four in 10 college students—38 percent—had used marijuana in the past year. That’s up from three in 10 in 2006.
Daily and close-to-daily use—20 or more times a month—went up as well. In 2014, 5.9 percent of college students report frequent use, up from 3.5 percent in 2007.
That represents “the highest level of daily use measured in the last 34 years,” the report says.
The report focuses on those attending college, which may or may not be representative of the 18- to 22-year-old group as a whole.
John Schulenberg , one of the study’s lead researchers, attributes this trend to a decrease in student perception about the risk of harm associated with marijuana use. The relationship between risk perception and marijuana use levels has always been a bit of a problem for public health experts. Many people’s perception of the risk associated with marijuana is a subjective appraisal of relative rather than actual risk perception; that is, as more and more and more objective information about marijuana confirms that it is not as dangerous as has been claimed in the past risk perception (relative to past claims) decreases—and use increases.
Public health experts focus on the actual risks associated with marijuana use; opponents of legal reforms focus on relative risk perception. They argue that reforms send the wrong message and thus increase use. The polemical, ideological argument of legalization opponents is that society can’t admit it made a mistake about marijuana because such an admission will lead to increases in marijuana use.
Schulenberg, though, is concerned about actual risk, which is present here. He writes, “We know through other research that frequent marijuana use can adversely affect academic performance and college completion.”
The MTF study also includes some other statistics, however, which may put college partying into context.
While marijuana use has been increasing, something else has been decreasing—binge drinking. Whether or not these two developments are related is uncertain from the MTF survey data, however.
Binge drinking is the consumption of five or more drinks in a row. The survey contains figures on how many college students report this behavior at least once in the last two weeks prior to the survey.
From 1998 to 2008 about 40 percent of college students engaged in this practice. Then this trend began to diminish, falling to 31.9 percent of college students in 2015. So, in the period framed by the recent press release from MTF, 2006 to the present, marijuana use has increased and binge drinking has decreased.
This trend, though, has actually been underway for the last 25 years, not just the last ten years. From 1991 to 2015 annual use of marijuana has increased from 26.5 percent of college students to 37.9 percent. Monthly marijuana use has increased from 14.1 percent to 21.1 percent. On the other hand, binge drinking has decreased: from 42.8 percent in 1991 to 31.9 percent in 2015.
Overall this indicates that in the 25 years from 1991 to 2015 annual marijuana use has increased by 43 percent, monthly marijuana use has increased by 49.6 percent, and binge drinking has decreased by 25.5 percent.
Another way of summarizing the long term trend is to look at the average annual rate of change over this 25-year period. Annual marijuana use by college students has increased from 1991 to 2015 by an average of 1.4 percent per year. The average annual rate of increase in monthly marijuana use has been 1.6 percent. In comparison, the prevalence of binge drinking during this 25-year period has fallen by an average of 1.2 percent per year.
The increase in marijuana use and decline in binge drinking is most notable over the last ten years, tracking closely to the decriminalization and legalization of cannabis over this period.
Another notable long-term trend is the increase in the “daily use” of marijuana, which again is defined as use on at least 20 out of 30 days in the last month. This has increased 155.6 percent among college students over the last 25 years, an average annual increase of 3.8 percent per year. (Such use declined in 2015, from 5.9 percent in 2014 to 4.6 percent in 2015.)
Last week’s Pot Matters: Pot and Motivation