Dr. Nora Volkow Speaking:
This study was trying to find out the e-cigarettes could have potential harmful effect for adolescents.
Classically it is recognized that e-cigarettes are likely to be much less toxic than combustible tobacco because you don't have the carcinogenic chemicals that you get when you are smoking a cigarette.
But on the other hand, nicotine is an addictive substance and by that nature it produces changes, neuroplastic changes in the brain
and so our concern has been whether early exposure of adolescence to nicotine could prime their brain to the rewarding effects of other drugs including tobacco,
regular combustible tobacco, and so this study was in fact addressing in a longitudinal way that whether kids that get exposed to electronic cigarettes and therefore exposed to nicotine are the more likely to have increased resources or smoking the regular cigarettes and that's actually what they seem to have found.