Tobacco Vapes Linked to Future Cannabis Use in Teens, Study Finds
Adolescents who use tobacco e-cigarettes are significantly more likely to report also using cannabis one year later, according to a new study by researchers at the University of Alabama at Birmingham and the University of Michigan.
Published in JAMA Network Open, the study examined two waves of nationally representative data from a cohort of nearly 10,000 “cannabis-naive” young people who had a mixture of past experience with tobacco e-cigarettes.
After adjustment for socioeconomic demographics and other risk factors, the researchers found that those who had used e-cigarettes at baseline were more than twice as likely to report using cannabis by the following year.
Strong association found between teen vaping and subsequent cannabis use
While there have been previous studies investigating the relationship between e-cigarette use and subsequent cannabis use in American teenagers before, these longitudinal studies have tended to focus on older data that may not reflect the recent drastic increase in teen e-cigarette use.
To address this gap, the new JAMA study examined data on e-cigarette and cannabis use taken from the two most recent available waves – wave 4.5 (2017-18) and wave 5 (2018-19) – of the Population Assessment of Tobacco and Health (PATH) Study. The analysis included 9,828 participants aged 12 to 17 from both waves of the survey who reported not using cannabis during the first wave.
They found that teens who reported having ever used e-cigarettes were around 2.6 times more likely than their non-vaping counterparts to subsequently report having used cannabis in the past year by the second survey wave. All-time e-cigarette users were also 3.2 times more likely to report having used cannabis within the past 30-days of the second survey.
The largest increase in likelihood was seen in teens who had reported using e-cigarettes within the past 12 months at baseline, who were 3.4 times more likely to endorse past 30-day cannabis in the wave 5 survey.
“Consistent with previous literature using data from 2013 to 2017, we found a significant and robust association between baseline e-cigarette use among cannabis-naive youth and subsequent cannabis use,” the researchers wrote.
Associations not reflected in population–level data
Although the researchers uncovered a strong association between e-cigarettes and subsequent cannabis use here, paradoxically, this same trend does not seem to be reflected at the national or population-level. Despite this and past studies indicating that e-cigarettes could be a “gateway” to cannabis use, other studies have shown that adolescent cannabis use has remained at relatively stable levels between 1995 to 2020.
The study authors offer a few explanations for this. Firstly, despite the strong individual associations, the actual size of the demographic affected (cannabis-naive teens who have tried e-cigarettes) is fairly small. For example, just 7.8% of cannabis-naive adolescents at wave 4.5 reported having ever used e-cigarettes; projected outwards, that could equate to just 6.3% of the entire youth population.
“Even if the estimated association were completely causal, our calculations [...] demonstrate that the estimated change in cannabis use at the population level due to e-cigarette use is less than 1 percentage point,” the researchers wrote.
Additionally, subsequent cannabis use does not necessarily mean sustained cannabis use. It may be that a sizable number of adolescent e-cigarette users choose to experiment with cannabis but never go on to become regular users.
Vaping, cannabis, and teen drug use
One of the main limitations of this study listed by the researchers is that the lack of geographic data on survey results made it impossible to analyze or control for states where adult-use cannabis had been legalized. While cannabis use would still be prohibited for young people, the difference this could make to a teen’s environment may be a worthy factor of study.
Fully understanding the relationship between e-cigarette use and cannabis use, and the factors that may lead to the initiation of either substance use, is an important part of developing effective public health strategies.
“One reason that understanding the correlates and outcomes of e-cigarette use is important is because e-cigarettes have rapidly increased in popularity to become a predominant substance of misuse among US youths,” commented Wilson Compton and Emily Einstein of the National Institute on Drug Abuse, writing in an accompanying invited commentary.
“The findings from this study illuminate the increased risk of future cannabis use as a possible consequence for adolescents who vape nicotine,” they continued. “This risk further highlights the compounding benefits of the primary prevention of vaping among adolescents in reducing the risk of exposure of the adolescent brain to nicotine, as well as reducing the risk of potential future exposure to cannabis and other negative outcomes.”
Cannabis exposure in adolescence can carry unique health risks, such as the development of a cannabis use disorder (CUD). As a demographic group, young adults already have the highest rates of CUD in the United States and are the least likely group to seek conventional treatment for their substance use problem.
Teen cannabis use has also been associated with impaired cognitive performance and a higher likelihood of using illicit drugs later in life. The combination of cannabis use and stress in adolescence has been linked with the development of long-term anxiety, while young cannabis users with both CUD and a mood disorder are known to be at a higher risk for self-harm.
