Nicotine — whether it comes from a traditional or electronic cigarette — could be a gateway drug to marijuana and cocaine, according to a study in the New England Journal of Medicine.
"While e-cigarettes do eliminate some of the health effects associated with combustible tobacco, they are pure nicotine-delivery devices," said co-author Dr. Denise B. Kandel, a professor of sociomedical sciences at Columbia University Medical Center and a research scientist at the New York State Psychiatric Institute.
Kandel and her husband, Eric, also of CUMC, reviewed her research dating back to 1975 that purported nicotine to be a gateway drug. But they weren't sure if that was because nicotine was a readily available drug or because there was something in it that altered other drugs' effects.
To investigate that, they also went over previous studies they did on mice that found that rodents exposed to nicotine had altered brain chemistry and activated genes that deal with rewards. They had given those mice nicotine and found that the cocaine worked at an amplified effect. And it only worked if mice were given nicotine first and cocaine second, not the other way around.
"One drug alters the brain's circuitry in a way that enhances the effects of a subsequent drug," Dr. Eric Kandel said.
Then, Dr. Denise Kandel looked at 2004 data and found that cocaine dependence was highest in users who started the drug while smoking cigarettes. This meshed with her findings that mice exposed to cocaine days after exposure to nicotine didn't show the amped effects of the drug — the nicotine and cocaine use had to be taken within a small window.
The scientists say that e-cigarettes pose the same risks for addiction to nicotine and, as a result, cocaine, as traditional cigarettes, especially during adolescence when the brain is developing.
"Nicotine clearly acts as a gateway drug on the brain, and this effect is likely to occur whether the exposure comes from smoking cigarettes, passive tobacco smoke or e-cigarettes," they said.
This is the latest study to call into question the safety of electronic cigarettes. Recent research showed that they emit toxic metals in the air, and the World Health Organization made recommendations last week calling for the prohibition of indoor smoking and sales and advertising to minors. The American Heart Association, too, issued a statement in August calling for regulations on e-cigarettes.
But not everyone agrees with the Kandels' conclusions.
"If their theory was correct, we should have expected a surge in cocaine use associated first with tobacco use and later with nicotine replacement products. In fact, we observe the opposite," Derek Yach, executive director of the Vitality Institute in New York City, which advocates for preventive health, told the Daily News. "Their message might apply to lab rats, but smokers trying to quit should follow the advice of the Royal College of Physicians and try e-cigs. Their risks of death and disease will decline as they succeed."
David Nutt, professor of neuropsychopharmacology at Imperial College in London, told an online discussion of tobacco scientists, "This is another example of journal press offices making routine studies 'news' by distorting the data interpretation."