We tested rs910083-C for association with each of the specific FTND items, as presented in Supplementary Table 3. The rs910083-C association was driven most strongly by TTFC (meta-analysis P=1.2×10−4). Its next most significantly associated FTND item was CPD (meta-analysis P=0.0011). TTFC is an indicator of withdrawal severity upon awakening40 and behavioral automaticity (habitual smoking without awareness or cognitive control7). Although TTFC has its distinct features (e.g., strongest predictor of cessation success among the FTND items), it is correlated with heaviness of smoking as captured by CPD.7
