Inflammatory markers in population studies of aging

PurposeTo review findings from major epidemiologic studies regarding risk factors for and consequences of elevated markers of inflammation in older adults.ResultsMost large, current epidemiologic studies of older adults have measured serum interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-alpha) and some studies also include more extensive batteries of measures including soluble receptors. There are few defined risk factors for the modest elevations in inflammatory markers seen with aging. These include visceral adiposity, lower sex steroid hormones, smoking, depression and periodontal disease. Of the markers assessed, IL-6 is most robustly associated with incident disease, disability and mortality.ConclusionThough correlated with age, the etiology of elevated inflammatory markers remains incompletely defined. Inflammation, especially IL-6 may be a common cause of multiple age-related diseases or a final common pathway by which disease leads to disability and adverse outcomes in older adults. Future research targeting inflammation should examine these pathways.

Research highlights
► Markers of inflammation are elevated in older adults.
► Visceral abdominal fat and lower sex steroid hormones are associated with higher levels of inflammatory markers.
► Of the markers assessed, IL-6 most robustly predicts disease, disability and mortality in old age.