Examining the relationship between biomarkers of immune aging and prevalent physical disability in the health and retirement study

Introduction: Large social inequities have been repeatedly observed in physical disability. While inflammation has been identified as a potential underlying biological mechanism to proxy immune processes, the general inflammatory measures available in many population health studies lack specificity in capturing the complex nature of immune function. Therefore, we sought to examine whether specific biomarkers of immune function are associated with the prevalence of physical disability.

Methods: We leveraged data from 8,543 adults (mean age = 69 years, 54 % women) in the nationally-representative Health and Retirement Study and employed gender-stratified Poisson regression models to examine whether a more aged immune profile, indicated by higher values in each marker of immune aging (CD8+:CD4+, EMRA CD4+:Naïve CD4+, EMRA CD8+:Naïve CD8+, and CMV IgG), was associated with a higher prevalence of activities of daily living (ADL) disability.

Results: After adjustment, among women, one standard deviation (SD) increase in CMV IgG was associated with 12 % higher prevalence of ADL disability (PR: 1.12; 95 % CI: 1.04, 1.21). Similarly each 1-SD increase in the CD8 + CD4 + ratio was associated with a 9 % higher prevalence of ADL disability (PR: 1.09; 95 % CI: 1.03, 1.16). No associations were observed among men across any of the immune measures.

Discussion: Our findings provide initial support that biomarkers of immune aging may serve as an important mechanism in understanding physical disability, particularly among women.