More than a third of the seniors surveyed reported smoking marijuana in the past 12 months.
Each year, the Monitoring the Future survey asks eighth-, 10th- and 12th-graders about their drug and alcohol use and their attitudes toward illegal substances. For 2013, more than 41,000 students from 389 U.S. public and private schools participated.
Only 2.4% of high school seniors reported using marijuana daily in 1993; this year that percentage nearly tripled – to 6.5 %. And it's not just the older students – more than 12% of the eighth-graders surveyed said they had used marijuana.
"It is important to remember that over the past two decades, levels of THC – the main psychoactive ingredient in marijuana – have gone up a great deal," said Dr. Nora Volkow, director of the National Institute on Drug Abuse, in a statement. "Daily use today can have stronger effects on a developing teen brain than it did 10 or 20 years ago. ... The children whose experimentation leads to regular use are setting themselves up for declines in IQ and diminished ability for success in life."
Teens also continue to abuse prescription medications such as Adderall, which is commonly used to treat attention-deficit hyperactivity disorder, and Vicodin. But while alcohol use is still high – close to 40% of seniors reported drinking in the past month – it's been on a steady decline since its peak in 1997.
Image: Marijuana, via Shutterstock