Changes in nicotine dependence among smokers using electronic cigarettes to reduce cigarette smoking in a randomized controlled trial.

Initiation of electronic cigarette use while continuing to smoke could potentially increase nicotine dependence. In this randomized trial aimed at helping smokers to reduce their cigarette intake, we found that use of an e-cig was associated with a reduction in cigarette dependence and an increase in e-cig dependence (in the condition with the highest nicotine concentration only), with no long term increase in total nicotine dependence or nicotine exposure.