Persistent infection, inflammation, and functional impairment in older Latinos

Abstract

Background: The objective of this study was to examine whether cytomegalovirus (CMV), herpes simplex virus type-1 (HSV-1), and C-reactive protein (CRP) are associated with functional impairment in older Latinos.

Methods: A cross-sectional analysis of a cohort study was conducted with a community-dwelling elderly population. The sample was a subset (N = 1559/1789) of participants in the Sacramento Area Latino Study on Aging (SALSA) ages 60-101 with available serum samples and functional impairment measures. Baseline serum samples were assayed for levels of immunoglobulin G antibodies to CMV and HSV-1 and for levels of CRP. Several measures were used to assess functional impairment, including activities of daily living (ADL), instrumental activities of daily living (IADL), and walking pace.

Results: CMV and CRP showed statistically significant graded associations with ADL functional impairment, even after controlling for age and gender. The relationship between CMV and ADL was slightly attenuated, and the confidence interval contained the null value when adjusted for total number of health conditions, body mass index, and household income. Only high levels of CRP were significantly related to ADL and IADL impairment even after adjusting for all other covariates.

Conclusion: Inflammation is clearly linked to physical functioning among aging Latinos. This study also suggests a role for CMV infection in relation to ADL impairment. Further research examining the influence of infection, immune response, and inflammation on longitudinal trajectories of physical functioning is warranted.

Figure 1. Mean CMV and HSV-1 Antibody Levels and Log CRP By Levels of Difficulty in Activities of Daily Living (ADL), Instrumental Activities of Daily Living (IADL) and Walking Pace

The plots show the mean and standard error bars for CMV and HSV-1 IgG antibody optical density units and (ln) natural log CRP levels by ADL and IADL difficulty status, and walking pace. ADL: Activities of Daily Living, IADL: Instrumental Activities of Daily Living. For ADL: ND= No Difficulty and D=Difficulty in ≥ 1 activities. For IADL: ND= No Difficulty in ≤ 2 activities and D= Difficulty in ≥ 3 activities. For walking pace: A= At or above average walking pace outdoors and B= Below average walking pace outdoors. OD=Optical Density Units, CMV=Cytomegalovirus, HSV= Herpes Simplex Virus 1 and CRP=C-reactive protein. *Significant at the P < .05