Ninth graders who use e-cigarettes and hookah are up to four times more likely to use marijuana in 11th grade, CNN reports. The findings come from a study of more than 2,500 teens from 10 public schools in Los Angeles. The study is published in Pediatrics.

“Once you start vaping, I think you become known as the person who vapes, who’s cool,” said Richard Miech, a principal investigator of Monitoring the Future, an ongoing study of adolescent drug use, who was not involved in the new study. “You get invited to parties where people are going to smoke cigarettes and smoke marijuana because you vape already. So there’s that social component.”

He added, “And I think there are probably other social pathways as well, other than just friendship networks. It probably changes your attitude. You probably vaped for a while and say ‘I don’t see any problem. I’m not dropping dead. I guess it’s not as dangerous as they’re telling me it is.’”