A new study published in the New England Journal of Medicine suggests that nicotine may be a gateway drug for other substances. The study found that nicotine use has a priming effect on the brain that increases the impact of cocaine use.
Researchers have known for many years that the majority of people who use cocaine or marijuana smoked cigarettes before turning to these drugs. In 2012, survey data showed that 87.9 percent of people with a lifetime history of cocaine use had smoked cigarettes prior to ever using cocaine. In contrast, only 3.5 percent began to use cocaine before they started smoking.
However, some experts have said that the “gateway hypothesis” is not the only explanation for this data. Another possible explanation is that multi-drug use simply reveals those people who are more vulnerable to drug use and addiction, and that addiction itself, rather than just using a drug, is what actually makes the brain more receptive to future dependency or addiction.
Mouse Study Shows Nicotine Enhances Cocaine Use
With this new study, researchers Denise and Eric Kandel believe that they have shown a clear molecular explanation for why people who use cocaine are overwhelmingly likely to have first been smokers. They found that nicotine use prior to trying cocaine enhances the effect of cocaine.
Using a mouse model, the researchers examined the effects of cocaine on their subjects after no exposure to nicotine, after nicotine use for one day and after nicotine use for seven days. They found that mice who were given only cocaine or who were given cocaine after one day of nicotine were both 58 percent more active than the controls. Mice who were given cocaine after seven days of nicotine were 98 percent more active than the control subjects.
In order to test the hypothesis that any drug use primes the brain for other drugs, the researchers also tested the effects of nicotine on mice after one and seven days of cocaine exposure. They found that a history of cocaine use did not affect the response to nicotine in the mice.
The Kandels believe that these conclusions are not necessarily incompatible with the hypothesis that a “common liability” for drug use contributes to multi-drug use. However, they do feel that their findings show a clear molecular explanation for the most common drug use sequence observed in people who have a history of both smoking and cocaine use.
In future studies, the researchers plan to evaluate whether alcohol and marijuana—other common precursors to cocaine use—create a similar gateway effect.
Implications for Electronic Cigarettes
At the conclusion of the study, the researchers addressed the potential implications of their research on the ongoing debate over electronic cigarettes. Many people believe that “vaping” has significantly fewer health risks than traditional smoking and may even be a valuable tool for helping smokers to wean themselves from the habit. However, many other people believe that e-cigarettes are simply too new, and current research too limited, to reach these conclusions. In a recent report, the World Health Organization urged a cautious approach to e-cigarettes, including a ban on indoor smoking until the effect of secondhand vapor on bystanders is proved to be harmless.
The Kandel study suggests that there may be some cause for concern over e-cigarettes, even if they are found to deliver nothing but nicotine into the body. Although nicotine has not been found to pose any physical health risks on its own, its apparent role as a gateway drug is cause for concern. This is especially true as more and more young people who have never tried traditional cigarettes are beginning to use e-cigarettes.