e-cigs are a gateway to cannabis too: evidence from Germany

In addition to the sizable literature showing that e-cigarettes are attracting many kids at low risk of initiating nicotine use with cigarettes to nicotine, many of whom go on to smoke cigarettes, there is strong consistent evidence that e-cigarettes are a gateway to the cannabis use in the USA. Now Ann-Kathrin Seidel and her colleagues have shown the same relationship among German youth.

Their paper “Use of Electronic Cigarettes as a Predictor of Cannabis Experimentation: A Longitudinal Study Among German Youth,” published in Nicotine and Tobacco Research, reports on a longitudinal study in which they followed 2040 German high school students who had never smoked cannabis at baseline for 18 months. They found that youth who had ever used e-cigarettes at baseline were nearly twice as likely to have smoked cannabis (adjusted relative risk 1.83) by the end of the study compared to youth who did not use e-cigarettes. They controlled for smoking and other risk factors.

Significantly, they found that the risk of going on to cannabis smoking was higher among the youth who did not smoke cigarettes at baseline (see figure above), with a 13.7 point increase in the percentage of never cigarette smokers who used e-cigarettes going on to smoke cannabis compared to a 4.4 point increase for the cigarette smokers who used e-cigarettes.

This finding, as well as the earlier work showing that many youth at low risk of initiating nicotine use with cigarettes in the USA start with e-cigarettes adds to the case against the “common liability” theory.

A study of US college students also found that the association of e-cigarette use and cannabis use is likely bidirectional, with stronger support for the link from e-cigarette use to later cannabis use, above and beyond cigarette use. Using PATH, we also found that cannabis use predicted tobacco use in youth.

This increase in risk of cannabis use associated with e-cigarette use was similar in magnitude to the increases found in the USA, despite the broad differences in the policy environment for both tobacco and cannabis between Germany and the USA.

Companies putting in Premarket Tobacco Product Applications (PMTA) to the FDA Center for Tobacco Products for authorization to sell their e-cigarettes in the USA is supposed to include a comprehensive assessment of the health impacts of allowing the sale of their products. Any comprehensive assessment of the health impacts of e-cigarettes should include this cannabis effect, which has been known for a long time. (The meta-analysis discussed above came out two years ago, in 2019, and reviewed papers from before that.) I doubt that any have.

While the FDA Center for Tobacco Products does not have jurisdiction to regulate consumer cannabis use, this indirect effect of e-cigarettes promoting youth cannabis use (which is illegal even in states that have legalized adult-use cannabis) is one more reason that allowing the sale of e-cigarettes is not “appropriate for the protection of public health.”

Here is the abstract:

Introduction: Experimentation with e-cigarettes is rising among youth, and there are concerns that e-cigarettes could be a new risk factor for initiating substance use. This study aimed to investigate whether e-cigarette use longitudinally predicts experimentation with cannabis.

Methods: During 2017-2019, a prospective cohort study with an observation period of 18 months was conducted with 3,040 students from Germany who had never used cannabis (mean age = 14.8, range: 13-18 years). A multiple poisson regression was used to investigate whether e-cigarette use was an independent predictor of future cannabis use.

Results: Lifetime e-cigarette use was reported by 29.4 % of the survey population (n = 894) at baseline, and 17.4 % (n = 529) initiated cannabis use during the observation period. Among e-cigarette ever users, the initiation rate was 34.5 % compared to 10.4 % of never users. Results were robust to adjustment for age, sex, migrant status, type of school, sensation seeking, peer cannabis use, the use of alcohol and conventional cigarettes (ARR = 1.83; 95 % CI: 1.48-2.25). Further analyses revealed that the association between e-cigarette use and cannabis experimentation was stronger among youth with low sensation seeking scores (ARR = .77, CI: .61-.97) and no conventional cigarette use (ARR = .48, CI: .37-.64) at baseline.

Conclusion: E-cigarette use is associated with a subsequent initiation of cannabis use. This association seems to be stronger for youth who have a lower risk for substance use in general. Future studies need to investigate whether this is only true for experimental or also more frequent cannabis use.

Implications: The study indicates a prospective association between e-cigarette use and initiation of cannabis experimentation independent of other risk factors. It suggests that e-cigarette use is more strongly associated with cannabis initiation for youth with a lower propensity to use substances (low sensation-seekers and non-smokers)

The full citation is: Seidel AK, Morgenstern M, Galimov A, Pedersen A, Isensee B, Goecke M, Hanewinkel R. Use of electronic cigarettes as a predictor of cannabis experimentation: A longitudinal study among German youth. Nicotine Tob Res. 2021 Aug 12:ntab166. doi: 10.1093/ntr/ntab166. Epub ahead of print. PMID: 34383071. It is available here.

Published by Stanton Glantz

Stanton Glantz is a retired Professor of Medicine who served on the University of California San Francisco faculty for 45 years. He conducts research on tobacco and cannabis control and cardiovascular disease/

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