Abstract
Objective: The present study sought to determine changes in plasma levels of catecholamine metabolites and serum levels of brain-derived neurotorophic factor (BDNF) among smokers with schizophrenia who were treated with varenicline. Methods: We compared plasma homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and serum BDNF levels across 4 groups, divided as follows: smokers with schizophrenia (S-Sc), nonsmokers with schizophrenia (NS-Sc), smokers who were otherwise healthy (S-HC) and nonsmokers who were otherwise healthy (NS-HC). In addition, we also examined plasma HVA and MHPG levels and serum BDNF levels prior to study initiation (T0) and 8 weeks after varenicline treatment (T8) in the S-Sc and S-HC groups. Results: Plasma HVA levels in the S-Sc group at T0 were significantly higher than in the NS-Sc, S-HC and NS-HC groups at the same time point (S-Sc at T0; 7.6 ± 1.6 ng/mL, NS-Sc; 4.8 ± 1.0 ng/mL, S-HC; 4.3 ± 0.9 ng/mL, NS-HC; 3.4 ± 1.4 ng/mL, p < 0.0001). Plasma MHPG levels in the S-Sc group at T0 were significantly higher than in the NS-Sc and S-HC groups; in addition, plasma MHPG levels in the NS-HC group were significantly higher than in the S-HC group (S-Sc at T0; 5.2 ± 0.7 ng/mL, NS-Sc; 2.8 ± 1.2 ng/mL, S-HC; 1.9 ± 0.8 ng/mL, NS-HC; 3.6 ± 1.3 ng/mL, p < 0.0002). Serum BDNF levels did not differ between the S-Sc and NS-Sc groups. In contrast, no difference in plasma HVA levels, plasma MHPG levels or serum BDNF levels was observed between T0 and T8. Conclusions: In conclusion, plasma levels of HVA and MHPG in the S-Sc group were significantly higher than in the NS-Sc group. Serum BDNF levels did not differ between the S-Sc and NS-Sc groups. Plasma HVA and MHPG levels and serum BDNF levels did not change after treatment with varenicline.
Highlights
Rates of smoking among individuals with schizophrenia are high, and several studies have estimated that these rates are two- to five-fold higher than those of the general population [1]
Varenicline is a smoking cessation aid approved by the Food and Drug Administration that acts as a selective partial agonist at α4β2 nicotinic acetylcholine receptors
In a study exploring homovanillic acid (HVA), MHPG, and brain-derived neurotorophic factor (BDNF) levels before and after 8 weeks of treatment with varenicline, we found that plasma HVA and MHPG levels in smokers were significantly higher than that in nonsmokers and that these levels did not change from baseline to 8 weeks after varenicline treatment in smokers [20]
Summary
Rates of smoking among individuals with schizophrenia are high, and several studies have estimated that these rates are two- to five-fold higher than those of the general population [1]. Individuals with schizophrenia are less likely to stop smoking than others groups of smokers [2]. This is of significance, as smoking has been identified as one of the single most important risk factors for medical disease and may result in elevated rates of mortality for individuals with schizophrenia. There are consistent and urgent recommendations for smokers with schizophrenia to quit smoking to improve health outcomes [3]. It has been reported to be more effective than other treatments, including bupropion and nicotine replacement therapy [4]. Large studies of this medication in patients with schizophrenia have yet been published. Uncontrolled case reports and case series have reported inconsistent effects, with some reporting good efficacy and tolerability and even improvements in cognitive symptoms [7,8,9], OPEN ACCESS
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