Background: Nicotine dependence is associated with an increased risk of mood and anxiety disorders and suicide. The primary hypothesis of this study was to identify whether the polymorphisms of two glutathione-S-transferase enzymes (GSTM1 and GSTT1 genes) predict an increased risk of mood and anxiety disorders in smokers with nicotine dependence.
Materials and methods: Smokers were recruited at the Centre of Treatment for Smokers. The instruments were a sociodemographic questionnaire, Fagerström Test for Nicotine Dependence, diagnoses of mood disorder and nicotine dependence according to DSM-IV (SCID-IV), and the Alcohol, Smoking and Substance Involvement Screening Test. Anxiety disorder was assessed based on the treatment report. Laboratory assessment included glutathione-S-transferases M1 (GSTM1) and T1 (GSTT1), which were detected by a multiplex-PCR protocol.
Results: Compared with individuals who had both GSTM1 and GSTT1 genes, a higher frequency of at least one deletion of the GSTM1 and GSTT1 genes was identified in anxious smokers [odds ratio (OR)=2.21, 95% confidence interval (CI)=1.05–4.65, P=0.034], but there was no association with bipolar and unipolar depression (P=0.943). Compared with nonanxious smokers, anxious smokers had a greater risk for mood disorders (OR=4.67; 95% CI=2.24–9.92, P<0.001), lung disease (OR=6.78, 95% CI=1.95–23.58, P<0.003), and suicide attempts (OR=17.01, 95% CI=2.23–129.91, P<0.006).
Conclusion: This study suggests that at least one deletion of the GSTM1 and GSTT1 genes represents a risk factor for anxious smokers. These two genes may modify the capacity for the detoxification potential against oxidative stress.
aCenter of Approach and Treatment for Smokers, University Hospital, Londrina State University
bDepartment of Psychiatry, Health Sciences Center
cDepartment of Pathological Sciences, Biological Sciences Center
dDepartment of Pathology, Clinical Analysis and Toxicology, Health Sciences Center, Londrina State University, Londrina, Paraná, Brazil
eIMPACT Strategic Research Centre, School of Medicine, Deakin University
fBarwon Health and the Geelong Clinic, Swanston Centre, Geelong, Victoria
gDepartment of Psychiatry, Orygen Youth Health Research Centre, Centre for Youth Mental Health, The Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, Australia
Correspondence to Sandra Odebrecht Vargas Nunes, MD, PhD, Center of Approach and Treatment for Smokers, University Hospital, Londrina State University, Campus Universitário/Cx, Postal 6001/Zip 86051-990, Londrina, Paraná, Brazil Tel: +55 43 33391178; fax: +55 43 33238210; e-mail: firstname.lastname@example.org
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Received March 3, 2013
Accepted October 25, 2013