But the vaping trends remained troubling.
More than 37 percent of high school seniors say they've vaped, which is up from just over a quarter a year ago.
The increases, based on a representative sampling of 13,850 high school students nationwide, translate to about 1.3 million more adolescents vaping in 2018, the researchers said.
"What we are seeing is a change in the patterns of drug taking among teenagers in that they are the lowest that we've seen for many years", said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which funded the report. "In fact, the investigators pointed out this is the largest increase they've ever seen in a substance product by youth in America", he noted. That previous study also revealed that more and more are vaping e-cigs.
However, marijuana use remains steady among high schoolers, with almost 6 percent of 12th graders reporting daily use.
"When we see rates of around 6 percent of high school seniors smoking marijuana on a daily or near-daily basis, that's an terrible lot of kids whose memory may be impaired and their brains aren't working at full steam at the exact time when they need to be", Compton said.
The study found a decline in teen use of other substances, including cigarettes, the use of which has dropped to its lowest level since 1975. This year, they polled 44,482 eighth-, 10th- and 12th-graders from 392 public and private schools. "However, it is urgent that teens understand the possible effects of vaping on overall health and on the development of the teen brain, and the potential for addiction".More news: Bomb kills eight in Syrian town held by Turkish-backed opposition forces
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Research also has shown that teens who vape are more likely to take up cigarette smoking, he added. "The consumer doesn't always know that, so they may not be aware that they're using nicotine when they're using this product". Therefore the ban on nicotine doses over 20mg/ml, is putting a stumbling block in that first step of a smoker's journey to a smoke free life.
That is double the amount of new e-cig users compared to past year.
Survey results indicate this could help.
Other e-liquid flavors seemed to be squarely aimed at kids, with packages that resembled frosted cookies and sour sweets. "They have less perception of risk from use of marijuana".
The federally funded survey released Monday is conducted by University of MI researchers and has been operating since 1975. "This increase was driven exclusively by nicotine vaping", the researchers wrote.
What about vaping? "Vaping mostly is an individual activity", said David Jernigan, a Boston University researcher who tracks alcohol use. Among 10th-graders, it jumped from 8.2 percent in 2017 to 16.1 percent in 2018, and among eighth-graders it rose from 3.5 percent last year to 6.1 percent this year. Only 1.7 percent of seniors reported misuse of Vicodin in the past year, compared to 10 percent 15 years ago.
Alcohol use and binge drinking also continue to decline among teens, according to the survey.