Relationship of Anxiety and Depression with Respiratory Symptoms: Comparison between Depressed and Non-Depressed Smokers in Singapore

The rising prevalence of smokers in the community, specifically psychiatric patients, necessitates smoking cessation as an important strategy for reducing the harmful effects of tobacco. This study aims to compare the profiles of depressed and non-depressed smokers and evaluate how psychiatric symptoms influence respiratory symptoms. A cross-sectional survey was administered to 276 non-depressed adult smokers in the community and 69 adult smokers who had been formally diagnosed with depression in the outpatient clinic of a University Hospital in Singapore. Participants were administered questionnaires on smoking attitudes and perceptions, psychiatric symptoms, and respiratory symptoms. Correlations and multiple regression analyses were conducted. The mean age of smokers in the study was 35.32 ± 13.05 years. Smokers in the community and psychiatric samples were largely similar on all of the sociodemographic factors, except that fewer depressed people were employed (χ² = 8.35, < 0.01). Smokers with depression also reported more attempts to quit smoking (χ² = 7.14, < 0.05), higher mean depressive, anxiety, and stress symptom (DASS) scores (t = -10.04, < 0.01), and endorsed more respiratory symptoms than smokers in the community (t = -2.40, < 0.05). The DASS scores, number of cigarettes smoked daily, years of smoking, general perception of smokers getting heart disease, and presence of lung disease were positively and significantly correlated with respiratory symptoms. On multiple regression, only anxiety symptoms (β = 0.26, p < 0.05) and the presence of lung disease (β = 0.22, p < 0.001) were significantly correlated with respiratory symptoms. Depressed smokers reported greater difficulty in quitting tobacco use, and they perceived more severe respiratory symptoms compared to non-depressed counterparts. Anxiety symptoms were positively associated with the severity of respiratory symptoms. Smoking cessation campaigns need to specifically target psychological symptoms in smokers and focus more psychoeducation on the risk of cardiovascular disease in the middle-aged population.