Yun et al. BMC Public Health 2012, 12:724 http://www.biomedcentral.com/1471-2458/12/724 R E S E A R C H A R T I C L E Association of smoking status, cumulative smoking, duration of smoking cessation, age of starting smoking, and depression in Korean adults Woo-Jun Yun1, Min-Ho Shin1, Sun-Seog Kweon1,2, So-Yeon Ryu3 and Jung-Ae Rhee1* Open Access Abstract Background: Many previous studies did not sufficiently control for several confounding factors that may affect the association between smoking and depression, such as socioeconomic status. We investigated the association between depression and smoking status, smoking exposure, duration of smoking cessation, and age of starting smoking while controlling for socioeconomic factors. Methods: This study was based on a community health survey performed in Jeollanam-do, South Korea, between September and November 2009. In total, 20,084 subjects (9,118 males and 10,966 females) were included in the analysis. Information on smoking characteristics, such as smoking status, pack-years of smoking, and age of starting smoking, was collected using a standardized questionnaire. Depression was defined using the Korean CES-D score. Results: The odds ratios (ORs) of depression were 1.35 (0.92–1.98) for former smokers and 1.77 (1.27–2.48) for current-smokers among males, and 2.67 (1.38–5.16) for former smokers and 3.72 (2.11–6.54) for current-smokers among females, after adjusting for other confounding factors. Compared to light smoking, heavy smoking was significantly associated with depression in males [OR = 3.97, 95% confidence interval (CI) = 1.42–11.14], but not in females (OR = 1.24, 95% CI = 0.73–2.09). No significant associations between depression and age of starting smoking and duration of smoking cessation were observed among former smokers. Conclusions: Our data demonstrate that smoking is strongly associated with depression, particularly among females. These findings suggest that depression prevention may need to be combined with smoking prevention and that different strategies may be needed for males and females. Background Epidemiologic [1-4] and clinical [5,6] studies have reported a strong association between smoking and de- pression. Several explanations for this association have been proposed. The first is that underlying environmental or genetic factors predispose individuals to both smoking and de- pression [2,7-9]. The second is that depression leads to smoking. Several studies reported that smoking may in- crease as a result of self-medication for depression [10-12]. The third is that smoking itself increases the * Correspondence: jarhee@healthis.or.kr 1Department of Preventive Medicine, Chonnam National University Medical School, Hak-1-dong, Dong-gu, Gwangju 501-746, Republic of Korea Full list of author information is available at the end of the article risk of depression [13-18]. Some studies found that smoking among adolescents increased the risk of depres- sion, and another reported that smoking was highly associated with depression in adults. However, in these studies, many confounding factors, such as socioeco- nomic status, which may affect the association between smoking and depression, were not sufficiently controlled. Furthermore, to our knowledge, no previous study has simultaneously evaluated several aspects of smoking sta- tus, including the amount of smoking, age of starting smoking, and duration of smoking cessation. The objective of this study was to investigate the cross-sectional association between smoking and depres- sion after controlling for socioeconomic factors and many aspects of smoking in population-based subjects. © 2012 Yun et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.