Findings on the degree to which smoking persistence is associated with nicotine withdrawal severity are mixed. While Breslau et al. (1992) and Madden et al. (1997) found no association, Xian et al. (2005), did. Our findings are mixed as well. We found no association between nicotine withdrawal severity and smoking persistence in the adolescent smokers, possibly due to little variance in those samples (91% of the girls and 93% of the boys were persistent smokers--most likely because they are earlier in their smoking careers). On the other hand, in the adults, smoking persistence was associated with more severe nicotine withdrawal. However, once other factors were taken into account the significant association remained only for the moderate class. This suggests that the association between smoking persistence and nicotine withdrawal severity is accounted for by other smoking behavior and psychopathology for the most severe class, while this is not the case for the moderate class. This relationship between smoking persistence and moderate nicotine withdrawal was maintained even when we expanded our criteria of smoking persistence from any smoking within the last month
