Children and teens who smoke — even if they have tried it only a few times — are more likely to be smoking daily during their 20s and less likely to have quit smoking by their 40s, according to a University of Minnesota study published Wednesday in the Journal of the American Heart Association.

Furthermore, the younger children are when they begin experimenting with cigarettes or the more often they smoke, the greater their chance of becoming full-fledge smokers during adulthood.

Children who first try smoking around the ages of 14 and 15 are, for example, six times more likely to be smoking in their 20s than those who puff on their first cigarette at age 18 or 19, the study found.

“We really should be doing everything we can to keep cigarettes out of the hands of children,” said David Jacobs, the study’s senior author and an epidemiologist at the U of M, in a phone interview with MinnPost.

“You have to keep never smoking until you are of age in order to have the real minimal risk of never becoming an adult smoker,” he added.

Although the prevalence of smoking has dropped dramatically among American teens in recent years — from 40 percent of 12 graders in 1995 to about 10 percent in 2018 — a still significant number of young people smoke. Each day, some 1,600 children and teens light up their first cigarette, according to the Centers for Disease Control and Prevention. And the number of young people using electronic cigarettes has risen rapidly recently — from 3.6 million in 2018 to 5.4 million in 2019.

Those discouraging figures formed the impetus behind legislation passed late last year by Congress and signed into law by President Trump that increased the minimum age for the sale of tobacco products from 18 to 21.

The current study isn’t the first, of course, to report that smoking during childhood raises the risk of continuing the habit during adulthood. In the United States, for example, it’s long been known that 9 in 10 adult smokers began smoking when they were kids. This study is the first, however, to follow the smoking habits of people from childhood into midlife. Most other studies have not been prospective, but have, instead, asked people to look back and recall when they started smoking. Such recollections can be inaccurate.

How the study was done

For the study, Jacobs and his co-authors analyzed smoking information on more than 6,600 people from the United States, Australia and Finland who were followed from childhood into midlife as part of the International Childhood Cardiovascular Cohort Consortium. The researchers looked specifically at smoking data collected at three points in the participants’ lives: when they were 6 to 19 years old (in the 1970s and 1980s), when they were in their 20s, and then again when they were in their 40s.

The analysis revealed that the age at which someone began smoking during childhood made a significant difference in whether they continued to smoke into their adulthood. Half of those who first tried smoking by age 14 were smoking daily in their 20s, compared to 33 percent for those who first tried at age 15 to 17 and 8 percent of those who first tried at 18 to 19.

Very few — 2.6 percent — of the participants began smoking when they were out of their teens.

“There’s a very small probability that you will become an adult smoker if you don’t start by adolescence,” said Jacobs.

The analysis also found that the intensity with which young people smoked — how often they lit up a cigarette — also predicted whether they became daily smokers in adulthood. For example, 86 percent of the participants who smoked daily between the ages of 15 and17 went on to do the same in their twenties, and 59 percent were still smoking daily in their 40s. By comparison, 49 percent of the participants who were regular, but non-daily, smokers between the ages of 15 and 17 went on to become daily smokers in their 20s, and 29 percent of them were still smoking daily in their 40s.

Yet, even children who only dabbled in smoking — puffing on a few cigarettes here and there — were at risk of becoming adult smokers. And the younger they were when they started such experimenting, the greater the risk. For example, 45 percent of the 13- to 14-year-old “triers” became daily smokers by young adulthood compared to 9 percent of 18- to 19-year-old ones.

“We’ve known for a long time that it’s much harder for a heavy smoker to quit smoking than for a light smoker,” said Jacobs.

“It’s very interesting that the intensity of the adolescent smoking is still visible in the quit rates during the 40s,” he added.

Limitations and implications

The study comes with several caveats. For example, the questionnaires used for the various groups of participants did not solicit uniform sets of information about childhood smoking, a factor that may have affected the findings. Also, young people, particularly young children, can have difficulty filling out questionnaires and therefore may not have provided accurate information about their early smoking behaviors.

In addition, the study did not consider smoking products other than cigarettes — most notably, electronic cigarettes. Jacobs believes, however, that when such research is done, the results are likely to be similar to those of the current study.

As Jacobs and his colleagues emphasize in their paper, their findings underscore the need to discourage young people from using any tobacco products, including banning the sale of such products to anyone under the age of 21.

“We really should do everything we can to keep them out of the hands of children, said Jacobs.

“If you have any influence with your child, the best thing you can do is give strong advice to not smoke,” he added.

For more information:  The study, which was funded in part by the National Heart, Lung, and Blood Institute, can be read in full on the Journal of the American Heart Association’s website.