Teenagers who use e-cigarettes may be at increased risk of "mental fog," a new study suggests.
The study, of thousands of U.S. teens, found that those who vaped were three times more likely than their peers to report problems with concentration, memory and decision-making.
The findings mirror those of a recent study of adults by the same research team: Men and women who used e-cigarettes had more complaints about their memory and thinking skills than non-users.
Neither study proves that vaping causes mental fog, said senior researcher Dongmei Li, an associate professor at the University of Rochester School of Medicine and Dentistry in New York.
It's possible, she said, that kids with cognitive complaints are drawn to e-cigarettes.
That point was echoed by Linda Richter, vice president for prevention research and analysis at the nonprofit Partnership to End Addiction in New York City. She wasn't part of the study.
E-cigarettes contain nicotine -- a stimulant that can give a short-term boost to concentration and memory, Richter explained.
This study, she noted, surveyed teens at only one point in time, and it's not clear which came first -- the vaping or the cognitive trouble.
But there are reasons to believe that vaping can cause those issues, both Li and Richter said.
"Like any addictive substance," Richter noted, "the longer-term effects of nicotine on the brain are opposite of its short-term effects."
Nicotine might heighten focus in new users. But over time, Richter said, "the brain adapts to the increased presence of nicotine by reducing its sensitivity to its effects -- eventually dulling the cognitive processes that initially reacted strongly to it."
There have long been concerns about nicotine's effects on the developing brain, in particular -- which is one reason why teens' rising use of e-cigarettes has become a public health issue.
The new study, according to Li, appears to be the first to link e-cigarette use with actual cognitive symptoms in teenagers.
Now, she said, researchers can look at whether kids' vaping habits precede those symptoms -- which would strengthen the case for cause and effect.
The findings -- published in the December issue of the journal Tobacco Induced Diseases -- are based on a 2018 federal survey of more than 18,000 U.S. teens.
Roughly 13% said they had ever used e-cigarettes, but had never smoked. A similar percentage had both smoked and vaped.
Meanwhile, about 18% of all teens reported having "serious" difficulty concentrating, remembering or making decisions.
It turned out that both vapers and smokers were more likely to have those complaints than their peers were. The odds were four times higher among kids who had used both e-cigarettes and tobacco, and three times higher among those who had only used e-cigarettes.
The link, Li said, was stronger among kids who started using e-cigarettes at a very young age.
Those who began vaping in middle school or earlier (but not smoking) were 77% more likely to have cognitive complaints than their peers who started vaping in high school.
According to Richter, it's possible that could reflect the less-developed brain's vulnerability.
But at this point, Li said, more research is needed to understand why vaping is connected to cognitive symptoms.
Nicotine is not the only ingredient in e-cigarettes. The battery-powered devices work by heating a liquid that contains various substances such as propylene glycol and glycerol. The heating creates a "vapor" that is inhaled.
There's evidence, Li said, that when inhaled, those e-cigarette ingredients are not benign -- possibly promoting inflammation in the lungs and blood vessels.
Even without a full understanding of the mechanisms, though, the message is clear, both Li and Richter said: Kids should not vape.
There are numerous reasons why, Li pointed out -- from the addictiveness of nicotine, to the wheezing and other respiratory symptoms linked to e-cigarettes, to the serious lung injuries some users have sustained.
Unfortunately, Li said, kids may not realize there are risks -- or be lured by social media images presenting vaping as "cool."
That's why prevention needs to start a young age, Richter said.
"Instead of waiting until a child is addicted to nicotine to intervene," she said, "we should be intervening much earlier to prevent the use of nicotine, as well as the addiction and other harms that will surely follow repeated use."
The Office of the U.S. Surgeon General has more on e-cigarettes.
SOURCES: Dongmei Li, PhD, associate professor, Clinical and Translational Science Institute, University of Rochester School of Medicine and Dentistry, Rochester, N.Y.; Linda Richter, PhD, vice president, prevention research and analysis, Partnership to End Addiction, New York City; Tobacco Induced Diseases, December 2020, online