Chronic systemic inflammation is associated with symptoms of late-life depression: The ARIC Study

Abstract

The current study examined how the pattern of systemic inflammation in the decades leading up to late-life relates to depression symptoms in older adults. Within the Atherosclerosis Risk in Communities Study, we measured high-sensitivity C-reactive protein (CRP), a non-specific marker of systemic inflammation, at three visits: 21 years and 14 years before, and concurrent with the assessment of depression symptoms, defined using the 11-item Center for Epidemiologic Studies Depression (CESD) Scale. We categorized participants into one of four groups based on their 21-year longitudinal pattern of elevated (≥3mg/L) versus low (<3mg/L) CRP (stable low; unstable low; unstable elevated; stable elevated). Analyses excluded participants with suspected depression during midlife. A total of 4,614 participants were included (age at CESD assessment: 75.5[5.1]; 59% female; follow-up time 20.7 years [SD 1.0]). Compared to participants who maintained low CRP levels (stable low), participants who had elevated CRP at 2 of 3 visits (unstable elevated; ß=0.09; 95% CI: 0.02, 0.17) and participants who maintained elevated CRP at all 3 visits (stable elevated; ß=0.13; 95% CI: 0.05, 0.21) had greater depression symptoms as older adults, after adjusting for confounders. After excluding participants with late-life cognitive impairment, only participants with stable elevated CRP demonstrated significantly greater late-life depression symptoms. In a secondary analysis, stable elevated CRP was associated with increased risk for clinically significant late-life depression symptoms. Chronic or repeated inflammation in the decades leading up to older adulthood is associated with late-life depression, even in the context of normal cognition.