We report no significant correlations between nicotine withdrawal and β2*-nAChR availability. This is consistent with the preclinical literature suggesting that the β2*-subtype does not play a critical role in the physical symptoms of nicotine withdrawal33, 76. In this study, subjects reported a mild-moderate level of nicotine withdrawal symptoms at baseline and over the course of the study, thus these results require replication in a larger sample with a greater range of nicotine withdrawal symptoms. Additionally, we did not obtain significant correlations between β2*-nAChR availability at 1 week of abstinence and clinical features. We previously found a negative correlation between the urge to smoke to relieve withdrawal symptoms and β2*-nAChR availability in the sensorimotor cortex at approximately 1 week of abstinence8. This discrepancy may be due to differences in correlational analysis methods, e.g., voxel-based analyses in the previous study versus spearman's rho correlations with regions-of-interest in the current study. Voxel-based analyses may be more sensitive to detecting significance in smaller brain regions, but that was beyond the scope of the current study. The lack of additional correlations at 1 week of abstinence was previously discussed8.
