A new study warns that e-cigarette smoking might open the doors to other drugs such as marijuana and cocaine.

Researchers at the Columbia University Medical Center stated in their study that e-cigarettes can be potential  "gateway drug" to addiction to other drugs. They presented their research at the 120th Shattuck lecture at the Massachusetts Medical Society.

The study co-author Denise B. Kandel, professor of sociomedical sciences (in psychiatry), Department of Psychiatry and Mailman School of Public Health, at Columbia University Medical Center (CUMC), explained that while e-cigarettes removed certain health effects related to combustible tobacco, they were pure nicotine-delivery devices.

According to researcher Dr. Eric Kandel, the findings gave a biologic study for the sequence of drug use seen in people. "One drug alters the brain's circuitry in a way that enhances the effects of a subsequent drug," he said in the university press release.

Kandel further explained that e-cigarettes had similar physiological effects on the brain as the traditional cigarettes. Apart from this, it might even pose the same risk of addiction to other drugs as regular cigarettes, especially in adolescence during a critical period of brain development nicotine clearly acted as a gateway drug on the brain. He said that this effect would happen despite smoking cigarettes, passive tobacco smoke, or e-cigarettes.

A recent study on e-cigarettes showed that they release more toxins in the air compared to conventional cigarettes. The smoke from e-cigarettes contains chromium, a toxic element, and nickel levels are four times higher than in traditional cigarettes. 

The study is published in the online edition of the New England Journal of Medicine.