Inflammatory markers and depressed mood in older persons: results from the health, aging and body composition study

Background Patients with major depression have elevated levels of inflammatory cytokines. We examined the link between inflammatory markers and depressed mood in a community-based sample of older people. Methods Data are from 3024 well-functioning older persons, 70–79 years of age, participating in the Health, Aging and Body Composition study. Depressed mood was defined as a Center for Epidemiologic Studies Depression scale score of 16 or higher. Plasma concentrations of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and C-reactive protein (CRP) were measured. Results Compared with the 2879 nondepressed subjects, the 145 persons with depressed mood had higher median plasma levels of IL-6 (2.04 vs. 1.83 pg/mL, p = .02), TNF-α (3.43 vs. 3.16 pg/mL, p = .05), and CRP (1.96 vs. 1.66 mg/L, p = .03). After adjustment for health and demographic variables, depressed mood was especially prevalent among persons who had a high (above median) plasma level for at least two of the inflammatory markers. Compared with those without high levels, for persons with a high level for two or all three markers the risk of depressed mood was 2.45 (95% confidence interval [CI] = 1.34-4.47) and 2.40 (95% CI = 1.27-4.53), respectively. The association between depressed mood and serum level of IL-6 was significantly stronger in men than in women. Conclusions In old age, depressed mood is associated with high levels of inflammatory markers, suggesting that depressed mood is causing and/or caused by systemic inflammation.