Youth who use electronic cigarettes are 3.5 times more likely to have smoked marijuana, according to results from a systematic review and meta-analysis published in JAMA Pediatrics.
“This study suggests 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,” Nicholas Chadi, MD, MPH, clinical assistant professor of pediatrics at the University of Montreal, told Infectious Diseases in Children. “E-cigarettes should not be recommended as a smoking cessation tool for young people, according to the American Academy of Pediatrics and other large professional associations in North America, because of the risk of increased cigarette/tobacco/drug use with e-cigarettes.”
According to Chadi and colleagues, e-cigarette use among young people aged 10 to 24 years has increased “substantially” in the past 5 years, with more than a third of high school seniors in the United States reporting use in the past year. They noted that recent studies have shown a strong association between electronic nicotine-delivery systems use and subsequent use of marijuana, alcohol and other drugs. Additionally, they pointed to longitudinal studies that have shown an association between marijuana use during adolescence and reduced cognitive abilities, as well as increased rates of mental health disorders.
Chadi and colleagues searched several databases for studies that compared rates of marijuana use among youth aged 10 to 24 years who had used e-cigarettes vs. those who had not. They used adjusted ORs of self-reported past or current marijuana use by the two groups as the main outcomes and measures. Independent reviewers assessed studies for inclusion and extracted data.
Chadi and colleagues included in their analysis three longitudinal and 18 cross-sectional studies with 128,227 participants. They found that odds of marijuana use were higher in youth who had used e-cigarettes than for those who had not (aOR = 3.47; 95% CI, 2.63-4.59; I² = 94%). The odds were significantly increased in youth who used e-cigarettes in both longitudinal studies (aOR = 2.43; 95% CI, 1.51-3.90; I² = 94%) and cross-sectional studies (aOR = 3.70; 95% CI, 2.76-4.96; I² = 94%), as well as in e-cigarette users aged 12 to 17 years (aOR = 4.29; 95% CI, 3.14-5.87; I² = 94%). The researchers reported a lower association in young adults aged 18 to 24 years (aOR = 2.30; 95% CI, 1.40-3.79; I² = 91%).
“Our findings mostly confirmed our hypotheses and reinforced what we know about adolescent brain development and vulnerability to addiction,” Chadi said. “What did surprise us was the strength of the association and how consistent studies were, even after controlling for several confounding factors like gender, race/ethnicity, previous substance use or mental health problems.” – by Joe Gramigna
Disclosures: The authors report no relevant financial disclosures.