Pathogen Burden, Blood Biomarkers, and Functional Aging in Community-Dwelling Older Adults.

Background: Lifelong accumulation of latent or persistent or repeated infections may be a contributing factor to the deterioration of physical and cognitive function associated with functional aging, but the evidence is limited and the biological underpinnings are unclear.

Methods: We profiled the seropositivity for common viral, bacterial, and plasmodial pathogens of local importance in community-living older adults in 2 studies involving 745 older adults (mean age 67.0, SD: 7.7 years), and 142 older adults (mean age 72.7, SD: 8.3 years). Pathogen load was related to different sets of age-related physical and cognitive measures of functional aging and the Frailty Index (FI), and plasma levels of biomarkers of inflammation, innate and adaptive immunity, and other physiological functions.

Results: High pathogen load was associated with impaired gait speed (GS; p < .015), functional mobility (performance-oriented mobility assessment [POMA]; p < .029), cognitive function (Mini-Mental State Examination [MMSE]; p < .05), and increased FI; p < .05). High pathogen load was significantly associated with C3a complement activity (p < .001), matrix metalloproteinase-7, macrophage inflammatory protein-1α (p < .05), and monocyte chemoattractant protein 2 (p = .028). Blood biomarkers did not fully explain the observed association between pathogen load and functional aging measures.

Conclusions: This study provides novel evidence linking lifelong cumulated numbers of latent, persistent, or repeated infection to functional aging, plausibly via inflammatory and immune and other biological factors.