Changes in plasma brain-derived neurotrophic factor levels in smokers after smoking cessation.

Several studies have reported that brain-derived neurotrophic factor (BDNF) might be associated with nicotine dependence. However, there are few studies on BDNF levels in humans with nicotine dependence. In the present study, we compared the differences in plasma BDNF levels in patients with nicotine dependence and in healthy nonsmokers, and we investigated serial changes in plasma BDNF levels in patients with nicotine dependence following smoking cessation. Forty-five voluntary smokers and 66 nonsmokers were recruited in this study. Of the 45 smokers, 12 were taking varenicline, 21 were using a nicotine patch, and 12 were unaided in their cessation effort by their own choice. Plasma BDNF levels were measured at baseline using an enzyme-linked immunosorbent assay (both smokers and nonsmokers) and at weeks 4 and 12 after smoking cessation (abstinent smokers only). A total of 19 smokers were able to remain abstinent during the entire study period. Baseline plasma BDNF levels were significantly lower in smokers compared to nonsmokers (F=4.410, p=0.002). The plasma BDNF levels in the abstinent smokers significantly increased from baseline after 4 weeks of smoking cessation (z=-2.86, p=0.004) but had a tendency of decrease in the period between weeks 4 and 12. We could not find differences in the plasma BDNF levels among the three smoker subgroups at week 12 following cessation. Changes in plasma BDNF levels might be related to the process of abstinence and the pathophysiology of nicotine dependence.