Chronic cough, not asthma, is associated with depression in the elderly: a community-based population analysis in South Korea

Background/Aims: Depression and allergic diseases, including asthma, are frequently reported as comorbid conditions. However, their associations have been rarely examined in community-based elderly populations. Methods: The analyses were performed using the baseline data set of the Korean Longitudinal Study of Health and Aging, which consists of 1,000 elderly participants (aged > 65 years) randomly recruited from an urban community. Depression was assessed using the Geriatric Depression Scale, Center for Epidemiologic Studies Depression Scale, and Hamilton Rating Scale for Depression. Major and minor depressive disorders were diagnosed by psychiatrists. Allergic conditions were assessed using structured questionnaires, lung function, and skin prick test. Quality of life and comorbidities were assessed using structured questionnaires. Results: Prevalence of asthma and major depressive disorder were 5.4% and 5.3%, respectively. The rate of depression was not significantly different between the non-asthmatic and asthmatic groups. No correlation was observed between the scores obtained using the depression scales and self-reported asthma. However, chronic, frequent, and nocturnal cough were significantly associated with depression and scores obtained using the depression scales, which remained significant in multivariate logistic regression analyses (chronic cough: odds ratio [OR], 3.23; 95% confidence interval [CI], 2.57 to 12.74; p = 0.04) Rhinitis was independently associated with high Mini-Mental State Examination scores (OR, 1.11; 95% CI, 1.05 to 1.17; p < 0.001) and low 36-item short-form (OR, 0.96; 95% CI, 0.80 to 0.98; p = 0.002). Conclusions: Depression may not be significantly associated with asthma and allergic diseases in elderly populations, but cough is a significant factor affecting depression.