Daily use of marijuana has increased among eighth, tenth, and twelfth grade youth, while alcohol use — at its lowest level since the survey began — and binge drinking have continued long-term declines, according to 2010 Monitoring the Future Survey (MTF) results released today.

MTF, an annual survey funded by the National Institute on Drug Abuse (NIDA), has measured self-reported drug use behavior and attitudes among high-school seniors since 1975 and among eighth and tenth graders since 1991.

Researchers, led by Lloyd Johnston at the University of Michigan’s Institute for Social Research, surveyed 46,482 eighth, tenth, and twelfth grade students in 396 public and independent schools across the country.

Prevalence measures of marijuana use rose in all three grade levels (measures included daily, past 30 days, past year, and lifetime use). When researchers combined data for all three grades, the one-year increases in marijuana use in all prevalence measures were statistically significant.

“Though this upward shift is not yet very large, its duration and pervasiveness leave no doubt in our minds that it is real,” said Johnston. “Perhaps the most troublesome part of it is that daily use of marijuana increased significantly in all three grades in 2010.”

From 2009 to 2010, daily marijuana-use rates increased from 1.0 to 1.2 percent for eighth graders, 2.8 to 3.3 percent for tenth graders, and from 5.2 to 6.1 percent for twelfth graders. That means that about one in every 16 high-school seniors who were surveyed self-reported daily use of marijuana.

Researchers defined daily use as using a drug 20 or more times in the last 30 days.

“These high rates of marijuana use during the teen and pre-teen years, when the brain continues to develop, place our young people at particular risk,” said Nora D. Volkow, M.D, director of NIDA. “Not only does marijuana affect learning, judgment, and motor skills, but research tells us that about 1 in 6 people who start using it as adolescents become addicted.”

The perceived risk of using marijuana, including risk of daily use, declined in all three grades.

“The increases in youth drug use reflected in the Monitoring the Future Study are disappointing. And mixed messages about drug legalization, particularly marijuana legalization, may be to blame,” said Gil Kerlikowske, director of the White House Office of National Drug Control Policy (ONDCP). “Such messages certainly don?t help parents who are trying to prevent young people from using drugs.”

While overall illicit drug use has gradually increased over the past three years among all three grades, it appears that most of the increase was due to marijuana. Illicit drug use, other than marijuana, has stalled after some years of declining.

One exception is ecstasy, which gained in popularity among eighth and tenth graders.

“There may well be a generational forgetting of the dangers of ecstasy as newer cohorts of youth enter adolescence. They have heard less about the dangers of the drug than did their predecessors,” said Johnston, “because they were quite young when the original ecstasy epidemic occurred.”

Meanwhile, alcohol use continued a long-term decline since 1980s. Alcohol use among all three grades decreased. In fact, the rate of alcohol use among twelfth graders is the lowest ever (since the study began in 1975), and the lowest among eighth and tenth graders since 1991 (when those grades were added).

Binge drinking — defined in the survey as five or more drinks in one sitting within the past two weeks — among twelfth graders declined significantly from 25.2 percent in 2009 to 23.2 percent in 2010. Occasions of heavy drinking declined among eighth and tenth graders, too, but the decrease was not statistically significant.

Use of flavored alcoholic beverages — a measure added since 2004 — has declined, although the percentage was not statistically significant. However, researchers noted, the “flavored alcohol beverage” category did not include alcoholic energy drinks.

Although past-30-days cigarette use among twelfth graders dropped below past-30-days marijuana use (19.2 percent and 21.4 percent, respectively), declines in overall cigarette use have stalled in all three grades.

Check out the links below for drug-by-drug information — including trends of teen prescription and over-the-counter drug use.

More information:

Overview of 2010 Monitoring the Future short- and long-term trends (Univ. of Michigan news release)

Data tables and figures from 2010 Monitoring the Future (Univ. of Michigan’s Monitoring the Future website)

National Institute on Drug Abuse’s Monitoring the Future Survey landing page (NIDA)