Some 6.1 percent of high-school seniors reported using marijuana this year on a "near daily" basis, up from 5.2 percent in 2009, according to the Monitoring the Future survey released by the National Institutes of Health. "Near-daily" use of marijuana means students reported using pot 20 times in the 30 days before the survey was taken.
Near daily marijuana use by 10th-graders climbed from 2.8 percent to 3.3 percent, and for eighth-grade students it edged up from 1.0 percent to 1.2 percent.
"These high rates of marijuana use during the teen and preteen years, when the brain continues to develop, place our young people at particular risk," said Dr. Nora D. Volkow, director of the National Institute on Drug Abuse.
The rates for marijuana use at any time during the year were 34.8 percent for seniors, 27.5 percent in 10th grade and 13.7 percent among eighth graders.
Volkow also said marijuana use affects learning and memory, and can be detrimental to educational achievement. The younger teens are when they start using drugs, the greater the likelihood they will become dependent, Volkow said.
"In clinical studies, epidemiology has shown that those who get exposed to marijuana before age 17 are more likely not just to become dependent on marijuana, but are more likely to become dependent on a wide variety of drugs," sid Volkow.
On the other hand, binge drinking is on the decline. While 23.2 percent of high school seniors reported having five or more drinks in a row, that's down from 25.2 percent a year earlier. The binge rate for this age group peaked at 31.5 percent in 1998.
Another shocking finding: teens haven't stopped smoking - they've just .
The study found that more high school seniors are smoking marijuana than tobacco. In 2010, 21.4 percent of seniors said they had toked pot within the past 30 days, while 19.2 percent said they had lit up cigarettes.
Why are more kids getting high?
One possibility is that teens may not view marijuana as a dangerous drug, according to the study's authors. "Fewer teens have shown disapproval of marijuana use over the past two or three years," the study stated.
The study also found that prescription drug abuse remains a major problem. University of Michigan Research Professor Lloyd D. Johnston said physicians should write pain medication prescriptions with lower doses because many teenagers abusing narcotics say they are using their own prescriptions.
"Thirty or 40 percent of the kids who misuse narcotics say they are using their own prescriptions, basically left over drugs. And most of the rest are either getting it from friends, or buying it from friends, who in turn may have had over-prescription," said Johnston.
On other topics the survey found:
- Use of ecstasy, which had declined in the early 2000s, is on the increase again. The study authors think this is because of the declining belief that the drug is dangerous. Younger teens, who haven't heard as much about potential risks tend to see it as safer than older teens.
- There was a small increase in teens injecting heroin, but only among 12th-graders.
- Use of cocaine remained low after declining from levels in the 1980s and 1990s.
The survey conducted by the University of Michigan covered 46,482 students in 396 schools.