Nearly a fifth of American high school seniors have used e-cigarettes recently, although tobacco smoking in this population is at an all-time low, according to the annual Monitoring the Future survey released Dec. 16.

“About 4% of 12th graders use e-cigarettes alone. They’ve never smoked a regular cigarette in their life,” Richard A. Miech, Ph.D., of the University of Michigan, Ann Arbor, one of the lead researchers on the study, said during a press conference held by the National Institute on Drug Abuse. This was the first year that data on e-cigarette use in teens were collected for the Monitoring the Future survey of drug, tobacco, and alcohol use in adolescents in 8th, 10th, and 12th grade. The survey has been conducted every year since 1975 by the University of Michigan and funded by NIDA.

Just over 17% of 12th graders reported past-month use of e-cigarettes. For 10th graders, the number was 16%, and for 8th graders it was nearly 9%. Daily cigarette smoking has decreased by half in the past 5 years across all age groups surveyed, with the largest decline being from just over 6% to about 3% in 10th graders.

Whether the decline in tobacco smoking correlates directly with the rise in e-cigarettes is unknown, NIDA director Dr. Nora Volkow said during the teleconference.

Nearly one-fifth of U.S. high school seniors have used e-cigarettes this year.

Particularly troubling, according to Dr. Miech, is that the 4% of 12th graders who reported using e-cigarettes exclusively tended to be college bound, a cohort he said typically does not use tobacco.

What actual harm e-cigarettes pose to youth, and whether they lead to other drug use are still open questions, according to Dr. Volkow.

“We can’t do a randomized, controlled trial of teens and give them e-cigarettes to see if they progress to harder drugs,” Dr. Miech said. “The best we can do is follow them as they age.”

Marijuana use among teens is steady and prevalent across all three age groups, according to the survey. More than a third of 12th graders (35%) reported past-year use of marijuana; nearly 6% reported daily use. “This constitutes one of the highest rates seen in any student population world wide,” said Dr. Volkow.

Similar to last year’s rates, 7% of eighth graders, 17% of 10th graders, and just over 21% of 12th graders reported smoking marijuana in the previous month.

The steady rates of marijuana use came as a welcome surprise, said Dr. Volkow, considering recent changes to marijuana laws at the state level and the way those changes might impact perception of marijuana use. In fact, there was a change across the entire study population in the perceived danger posed by marijuana, down from 27% 5 years ago to 16% this year.

In states with medical marijuana laws, 40% of 12th graders who reported using marijuana in the past year said they had used edible marijuana products, compared with 26% of seniors who lived in states without such legislation.

Whether digested versus smoked cannabinoids pose greater health risks to teens “is relatively new for us,” Dr. Volkow said, noting that there are little data on how quickly cannabinoids consumed orally may enter the bloodstream. “When you smoke a drug, it gets into the brain very rapidly, and that is associated with stronger rewarding affects and more addictiveness, but it also is associated with better control of how much you ingest.”

“It’s pretty obvious when people are smoking a joint – the feedback is quick,” said Dr. Lloyd D. Johnston, lead investigator for Monitoring the Future, also of the University of Michigan. Ingested marijuana is different and variable, he noted, both in the amount of marijuana consumed and in the time it takes for the drug to take effect. “I think it’s considerably more dangerous.”Understanding the bioavailability and the pharmacokinetics of edible marijuana is a pressing research concern at NIDA, Dr. Volkow said.

Nonmedical use of prescription drugs is down overall among survey respondents. Nonmedical use of Vicodin declined from 9.7% 5 years ago to 4.5% this year. For oxycontin, nonmedical use declined from 4.8% to 3.3%.

Alcohol use, particularly binge drinking in 12th graders, also is losing popularity. At its peak in 1998, 31.5% of 12th graders reported binge drinking; less than 20% did so in 2014. A decline in the use of synthetic marijuana (also known as K2/Spice) was also noted, down from nearly 8% in 12th graders to just under 6%. Heroin, crack cocaine, and methamphetamine use remained low and relatively unchanged from last year.

“Over all, this is good news,” said Dr. Volkow.

Monitoring the Future is unusual in that the data, gathered from nearly 42,000 U.S. students at 377 public and private schools across the country, are reported in the same year they are gathered.

wmcknight@frontlinemedcom.com

On Twitter @whitneymcknight

E-cigs surpass smoked tobacco in U.S. teens; marijuana use among ‘highest’ worldwide