Adolescents who smoke cigarettes are more likely to start vaping, and the reverse is also true: vaping can lead to smoking. In former smokers, vaping can also increase the risk for relapse back to smoking. While some young people report vaping to help them quit smoking, most continue to smoke resulting in dual use. The high rate of dual use suggests that vaping could prolong smoking and increase harms in young people who would have otherwise quit. Biomarker data show that dual users are exposed to higher levels of harmful chemicals known to cause tobacco-related illnesses compared to those who only smoke.

Genetic variation influences cigarette smoking. People with gene variants that increase the rate at which nicotine is inactivated smoke more cigarettes, have a higher risk for tobacco-related illnesses, and are less likely to quit, compared to people with slow nicotine metabolism. In ALSPAC, we propose to study whether youth smokers with genetically faster nicotine metabolism have a higher risk for becoming a dual user and continuing smoking once they start vaping. In former smokers, we will test whether faster nicotine metabolism increases relapse back to smoking among vapers. As a secondary goal, we will also test whether other genes, for example those that alter the response to nicotine in the brain, also influence the risk for vaping.

The reasons underlying the popularity of vaping and dual use among youth are not well understood, and our work will show whether genetic factors play a role.