The severity of nicotine dependence was assessed at intake with the Fagerström Test for Nicotine Dependence (FTND)48, and craving and nicotine withdrawal symptoms were assessed with the Urge to Smoke Questionnaire (QSU)49 and the Minnesota Nicotine Withdrawal Scale (MNWS)50, respectively, at baseline, e.g., on the day of their intake prior to quitting smoking, and on each day of their participation in [123I]5-IA scans. The QSU has two main factors, the intention/desire to smoke (QSU-Intent) and relief of negative affect and withdrawal (QSU-Relief).
