Nicotine & Tobacco Research, Volume 14, Number 5 (May 2012) 540–546 540 doi: 10.1093/ntr/ntr247 Advance Access published on December 16, 2011 © The Author 2011. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com Introduction Depressive symptoms are closely associated with nicotine dependence and could play an important etiological role in the comorbidity of depression and nicotine dependence (Leventhal, Kahler, Ray, & Zimmerman, 2009). Smokers are more likely to report symptoms of depression and anxiety than nonsmokers (Schmitz, Kruse, & Kugler, 2003). Similarly, current smokers have an elevated risk of major depression relative to nonsmokers or former smokers (Grant, Hasin, Chou, Stinson, & Dawson, 2004). Studies of major depression, anxiety disorder, and sub- stance use disorders have found that persons who suffer from mental illness have higher rates of lifetime and current smoking and lower quit rates compared with persons who do not suffer from mental illness (Breslau, Novak, & Kessler, 2004). Other studies have shown that tobacco smoking is highly prevalent among people with bipolar disorder and schizoaffective disorder and is associated with a worse prognosis (Dodd et al., 2010). Some hypotheses have been postulated for the elevated risk of smoking in people with mood disorders. These include the “self-medication theory,” which proposes that depression leads to smoking because nicotine dependence may have mood mod- ulatory effects. A second theory holds that smoking and depres- sion have common environmental or genetic risk factors. A third one suggests that depression is a consequence of brain dysfunction induced by smoking (Dome, Lazary, Kalapos, & Rihmer, 2010). Smoking may increase the risk for the development of depression (Pasco et al., 2008). This may in part be due to the role of dopamine in mood regulation (Malhi & Berk, 2007) and that smoking alters the set point of the dopamine reward system in the nucleus accumbens (Dani & De Biasi, 2001). Some have suggested that there may be common neurobiological substrates for substance abuse and mental disorders (Volkow, 2005). The association between substance use disorders and psy- chiatric disorders could be linked by the role of stress in the Abstract Introduction: Both smoking and depression have been associ- ated with increased inflammatory markers. As there are few studies on inflammatory markers that distinguish between depressed and nondepressed smokers, it is unclear if there is a cumulative impact of these mediators of inflammation. The aim of this study was to investigate inflammatory markers in tobacco smokers and compare depressed and nondepressed smokers. Methods: Smokers (n = 155) were recruited from the Cigarette Smoking Cessation Service, Londrina. Mental health status was assessed using the Diagnostic Interview for Research, in accordance with the International Classification of the Disorders-10th (ICD-10). Demographic information was col- lected by self-report questionnaire, and the Fagerström Test for Nicotine Dependence was administered. Blood specimens were simultaneously collected and measured for C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Results: Depressed smokers had significantly higher levels of hs-CRP (p = .05), IL-6 (p = .039), and TNF-α (p = .021) compared with nondepressed smokers. Depressed smokers were also significantly more likely than nondepressed smokers to have been hospitalized in the previous month (p < .032), to suffer from cardiovascular disease (p < .001) and lung disease (p < .003), and to have more work-related disability (p = .001). Conclusions: These findings demonstrate that depressed smokers had higher hs-CRP, IL-6, and TNF-α levels than non- depressed smokers and had worse physical health outcomes and greater work-related disability. This may have important impli- cations in identifying shared risk pathways for depressive and somatic disorders. Original Investigation A Comparison of Inflammatory Markers in Depressed and Nondepressed Smokers Sandra Odebrecht Vargas Nunes, M.D., Ph.D., 1 Heber Odebrecht Vargas, M.D., M.Sc., 1 Juliana Brum, M.D., 2 Eduardo Prado, M.D., 2 Mateus Mendonça Vargas, 2 Márcia Regina Pizzo de Castro, M.Sc., 2 Seetal Dodd, Ph.D., 3,4 & Michael Berk, M.D., Ph.D. 3,5,6 1 Department of Psychiatry, Health Sciences Center, Londrina State University, University Hospital, Londrina, Brazil 2 Cigarette Smoking Cessation Service, Londrina State University (UEL), University Hospital, Londrina, Brazil 3 Department of Psychiatry, University of Melbourne, Parkville, Australia 4 School of Medicine, Deakin University, Geelong, Australia 5 Orygen Youth Health Research Centre, Parkville, Australia 6 Mental Health Research Institute, Parkville, Australia Corresponding Author: Sandra Odebrecht Vargas Nunes, M.D., Ph.D., Universidade Estadual de Londrina, Av Adhemar e Barros, 625, Londrina, Paraná 86050-190, Brazil. Telephone: 55-43-33391178; Fax: 55-43-30375627; E-mail: sandranunes@sercomtel.com.br Received February 9, 2011; accepted September 23, 2011 Downloaded from https://academic.oup.com/ntr/article/14/5/540/1052203 by guest on 17 November 2021