Teenage Vaping Linked to Cannabis Use, Finds Study
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Adolescents and young adults who use e-cigarettes are significantly more likely to use cannabis than their counterparts who have never vaped, say the authors of a new review.
The systematic review and meta-analysis, which was published in JAMA Pediatrics this week, analyzed the results of 21 previous academic papers, evaluating data from some 128,000 participants.
Researchers found that young people who used e-cigarettes were on average 3.5 times more likely to admit to current or past cannabis use. The researchers hypothesize that this link between e-cigarettes and cannabis use might arise due to nicotine exposure on the young developing brain, but are careful to note that their study alone doesn’t directly prove causality.
Younger brains show stronger correlation
Once of the most interesting findings to come out of the review was the presence of a seemingly strong correlation between age, e-cigarette use, and subsequent cannabis use.
Young adults (aged 18 to 24 years) who reported using e-cigarettes or vape products were 2.3 times more likely to use cannabis, but for adolescents (aged 12 to 17 years) the odds were much higher; those with a history of e-cigarette use were on average 4.3 times more likely to go on to use cannabis.
“Adolescents have a brain that’s still changing and developing,” said Dr Nicholas Chadi, the lead author of the study to CNN.
Once a young brain is exposed to nicotine or a similar addictive substance, it “tends to be sensitized to other substances; it tends to seek a thrilling, rewarding sensation,” said Chadi. “And so other substances like marijuana become more appealing.”
Pre-existing research has shown a link between tobacco cigarette use and cannabis use, but this study is an important bridge in establishing whether this link continues to hold given the rising popularity of alternative tobacco products, such as e-cigarettes and vape products, among young people.
“E-cigarettes are often considered benign or harmless by youth and their families,” Chadi told Reuters. “What this study suggests is that e-cigarettes (most of which contain nicotine) should be considered harmful, in a similar way as other substances like alcohol and tobacco, which have also been associated with increased marijuana use.”
The review also found a stronger correlation between e-cigarette use and cannabis use in North American countries, as compared to similar studies carried out in Europe. The researchers note that cannabis use is more common in North American countries than European ones, where tobacco cigarette use is far more prevalent. The correlation observed in this review then could be down to European youths generally being less inclined to use cannabis, say the researchers. Additionally, variation in laws surrounding tobacco sales could be a factor, with many European countries setting the minimum legal age of purchase for tobacco products at 16-18 years old. Comparatively, fifty percent of the US population lives in an area where the minimum age of purchase for tobacco is 21 years old.
A larger association between e-cigarette use and cannabis use was also seen in studies published after the year 2017, which researchers say “could be a reflection of the rapidly evolving landscape” of e-cigarette and vape products.
Limitations of the study
The researchers note a couple of major limitations on the review. Firstly, none of the experiments that matched the review criteria were controlled experiments, and so nothing could definitively prove that vaping has a direct impact on cannabis use.
Additionally, to increase the scope of the review the researchers looked at all cannabis use – whether the individual used the drug regularly, or had only tried cannabis once many years ago – so it wasn’t possible to draw any conclusions about whether vaping might also be associated with an increased frequency of cannabis use.
“We can’t prove a link of causality,” said Chadi to the Toronto Star. But given the large number of studies that indicate similar trends, “we have a good reason to think that exposure to vaping is part of the cause of initiation to marijuana.”