Inflammatory biomarkers predict depressive, but not anxiety symptoms during aging: the prospective Sydney Memory and Aging Study

Abstract

This study addresses the paucity of research on the prospective relationship between a range of inflammatory markers and symptoms of depression and anxiety during aging. In the Sydney Memory and Aging Study, the relationships between remitted depression, current and first onset of symptoms of depression or anxiety (Geriatric Depression Scale and Goldberg Anxiety Scale (GDS, GAS), and markers of systemic inflammation (C-reactive protein (CRP), interleukins-1β, -6, -8, -10, -12, plasminogen activator inhibitor-1 (PAI-1), serum amyloid A, tumor necrosis factor-α, and vascular adhesion molecule-1) were investigated. The sample consists of N=1037 non-demented community-dwelling elderly participants aged 70-90 years assessed at baseline and after 2-years. All analyses were adjusted for gender, age, years of education, total number of medical disorders diagnosed by a doctor, cardiovascular disorders, endocrine disorders, smoking, body mass index, currently using anti-depressants, NSAIDS or statins and diabetes mellitus. The results show a significant linear relationship between increasing levels of IL-6 and depressive symptoms at baseline only, whereas IL-8 was associated with depressed symptoms at baseline and at 2 years follow-up. In addition, IL-8 was associated with first onset of mild to moderate depressive symptoms over 2 years. Logistic regression analyses showed that PAI-1 (OR=1.37, 95% CI=1.10-1.71, p=0.005) was associated with remitted depression. Results for anxiety symptoms were negative. The findings are suggestive of IL-6 and IL-8 being associated with current symptoms and IL-8 being associated with first onset of depressive symptoms, whereas PAI-1 could be regarded as a marker of remitted depression.