Like conventional cigarettes, e-cigarettes may function as a “gateway drug”—a drug that lowers the threshold for addiction to other substances such as marijuana and cocaine, according to researchers at the Mailman School of Public Health and Columbia University Medical School. The findings were presented by Dr. Denise Kandel, professor of sociomedical sciences, and Dr. Eric Kandel, University Professor and co-director of the Mortimer B. Zuckerman Mind Brain Behavior Institute, to the Massachusetts Medical Society and published online in the New England Journal of Medicine.

[Photo: Dr. Denise Kandel]

“While e-cigarettes do eliminate some of the health effects associated with combustible tobacco, they are pure nicotine-delivery devices,” said Dr. Denise Kandel, who is also in the department of psychiatry at Columbia and a research scientist at the New York State Psychiatric Institute.

Dr. Denise Kandel’s earlier work on the gateway hypothesis and the role of nicotine as a gateway drug, reported in a Science paper in 1975, as well as subsequent studies with colleagues on the gateway hypothesis, found that when mice are exposed to nicotine, it alters their brain biochemically and induces activation of a reward-related gene. As a result, nicotine primes the animals’ subsequent response to cocaine, providing a molecular basis for nicotine as a gateway drug for cocaine.

In a further analysis of 2004 epidemiologic data from a large, longitudinal sample, Dr. Kandel reported that the rate of cocaine dependence was highest among users who started using cocaine after having smoked cigarettes, findings that provided a biologic basis for the sequence of drug use observed in people.

E-cigarettes have been touted as a tool to curtail the use of conventional cigarettes and reduce the harmful health effects of combustible tobacco. But in light of the skyrocketing popularity of e-cigarettes, particularly among adolescents and young adults, the researchers say that more effective prevention programs need to be developed for all products that contain nicotine.  And while e-cigarettes may pose the same risk of addiction to other drugs as regular cigarettes, especially in adolescence during a critical period of brain development, they note that it is still unknown whether e-cigarettes will prove to be a gateway to the use of conventional cigarettes and illicit drugs.

“The recent legalization of marijuana in Colorado and Washington has rekindled the debate about whether marijuana is a gateway drug,” said Dr. Kandel. “Yet both proponents and opponents of legalization have overlooked the role of nicotine in leading to the use of illicit drugs and to addiction.”

The article is titled, “A Molecular Basis for Nicotine as a Gateway Drug.” The study was supported by grants from the Howard Hughes Medical Institute and the National Institutes of Health (R01 DA024001) and the National Institute on Drug Abuse (K5 DA00081).