Young adults who use e-cigarettes or “vape” are four times more likely to smoke cigarettes, according to a University of Pittsburgh study released Monday.

The research, published in the American Journal of Medicine, provides evidence that e-cigarettes are not a smoking cessation tool, but rather a gateway to cigarette addiction, experts said.

“Early evidence on the potential value of e-cigarettes for cessation or reduction of cigarette smoking has been mixed,” said lead author Dr. Brian A. Primack, director of Pitt’s Center for Research on Media, Technology and Health, and dean of Pitt’s Honors College. “Our study finds that in nonsmokers, e-cigarettes make people more likely to start smoking. This supports policy and educational interventions designed to decrease the use of e-cigarettes among nonsmokers.”