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

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.

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.

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.

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.