Most individuals who have ever tried smoking begin experimenting with tobacco as minors, and the typical adult with a smoking habit established that pattern between 17 and 18 years of age. Fortunately, the long-term consequences of smoking during youth are quite low—mortality effects among those who quit before age 25 remain negligible—but, those who continue after age 40 increase their risk for severe related health consequences, including early death, by about 90 percent. Therefore, in order to effectively allocate finite public health resources, it is important to understand the factors that could influence whether individuals transition from experimental use in youth to habitual smoking in adulthood.

To this end, a recent study published in the American Journal of Preventive Medicine seeks to elucidate “how different patterns of minors’ cigarette experimentation relate to habitual smoking and vaping from 18 to 21 years.” To do so, Abigail Friedman et al. collected and analyzed data from 1,424 “ever-triers” between 18 and 21 years old—most were white (81.5 percent) males (59.9 percent), whose parents had completed at least one year of college (60.2 percent) and these demographics approximately matched the sample characteristics of a 2015 National Health Interview Survey to examine the relationship between current and past smoking behaviors among a national sample of youth who had tried combustible cigarettes, e-cigarettes or both. To understand patterns of cigarette use initiation, the survey included retrospective questions about when respondents first tried combustible and electronic cigarette products. To understand patterns of current cigarette use, the survey included binary indicators to measure four dependent variables: daily smoking; daily vaping; current established smoking and; current established vaping.

Consistent with prior research, Friedman and colleagues found that a majority of the sample (77 percent) had experimented with either combustible or e-cigarettes before turning 18 years old. The vast majority (83 percent) of these individuals had experimented with combustible cigarettes first, and just over half (51 percent) had at least one parent who smoked combustible cigarettes. The study participants also tended to be younger when they tried their first combustible cigarette than when they tried their first e-cigarette: 15 versus 17 years of age, respectively.

The study reports three key findings. First, roughly one-third of experimenters were not current smokers. Second, combustible cigarette experimentation was more predictive of developing a smoking habit, and third, e-cigarette use alone might reduce the likelihood of developing a later habit of smoking combustible cigarettes. All of this is to say that overall, Friedman et al. found that combustible cigarettes play a much bigger role in future tobacco-use habits than e-cigarettes. Compared to individuals who did not experiment with cigarettes as minors, those who tried only combustible cigarettes prior to 18 years old had 175 percent increased odds of being an established smoker in young adulthood and 161 percent increased odds of becoming a daily smoker of combustible cigarettes.

On the other hand, those who tried only e-cigarettes as a minor were actually less likely to be a habitual smoker of combustible cigarettes later on, with a 78 percent decrease in odds. And those who experimented with both combustible cigarettes and e-cigarettes as a minor were more likely to develop a regular habit of smoking combustible cigarettes. In these cases, those who started out with combustible cigarettes were more than 2 to 3 times as likely to continue smoking combustible cigarettes compared to those who tried e-cigarettes first.

Regarding the vaping dependent variables, Friedman and colleagues found much smaller effects. Experimentation with both combustible and e-cigarettes as a minor was correlated with an increased likelihood of developing a vaping habit, especially for individuals who tried e-cigarettes first. However,  early experimentation with just one form of cigarette had no significant effects. Study participants were also significantly more likely to smoke—either combustible or e-cigarettes—in early adulthood, if at least one parent used a given product when the respondent was 16 years old.

Considering these findings in the context of a public health agenda, Friedman et al. stress the relative importance of preventing experimentation with combustible cigarettes. In short, they argue that “new efforts to reduce e-cigarette use should not take resources away from effective smoking-prevention programs.” Furthermore, given the small but significant effects of parental smoking on youth cigarette use, this is another area where the authors recommend intervention and further research.

Despite such recommendations, Friedman et al. acknowledge a couple of weaknesses to be considered when applying this new knowledge going forward. First, because individuals who experiment with only e-cigarettes often use flavoring-only zero-nicotine products, their inclusion in the study might be skewing the results. It would thus be valuable for future studies to ask participants whether or not they are vaping products that actually contain nicotine. Second, given the relative novelty of e-cigarettes on the U.S. market, the cohort studied did not have access to these products during childhood.

Notwithstanding these avenues for future research, this study provides practical information that can shape the prioritization of public health efforts and can be used to guide the development of campaign messages.