Association between smoking cessation and depressive symptoms according to cessation duration, pack-years, and tobacco product type: a nationwide cross-sectional study in Korea

Background Depression, a growing global mental health concern, has multifactorial causes and is frequently associated with cigarette smoking. There is a persistent misconception that quitting smoking worsens depressive symptoms. This study examined the association between smoking cessation and depressive symptoms and whether this relationship varies according to cessation duration, cumulative tobacco exposure, and tobacco product type. Methods A total of 231,469 participants from the 2024 Korea Community Health Survey were included. The Patient Health Questionnaire-9 was used to evaluate depressive symptoms. Participants’ smoking status (never, current, or former smoker), cessation duration, cumulative tobacco exposure, and primary tobacco product type were determined based on the survey responses. Multiple logistic regression analyses were conducted to examine associations between smoking cessation and depressive symptoms in this cross-sectional dataset. Results Compared with never-smokers, both former and current smokers showed elevated odds of depressive symptoms. However, former smokers showed lower odds than current smokers (men: aOR = 1.18 vs. 1.36; women: aOR = 1.64 vs. 1.96). Among former smokers, those who had quit for less than a year showed the highest odds of depressive symptoms, with a gradual decline as cessation duration increased. In men, higher pack-years corresponded to greater odds of depressive symptoms. Dual former smokers of conventional and electronic cigarettes demonstrated significantly higher odds of depressive symptoms than exclusive conventional cigarette users. Conclusion Smoking cessation was associated with lower odds of depressive symptoms compared with current smoking, although former smokers still showed higher odds of depressive symptoms than never smokers. These findings should be interpreted cautiously given the cross-sectional design, which precludes causal inference and raises the possibility of reverse causality. Among former smokers, women, recent quitters, individuals with higher cumulative exposure, and dual users may represent subgroups vulnerable to depressive symptoms.