Life course socioeconomic disadvantage and persistent infection burden: Links to cellular immunosenescence in U.S. young adults

BACKGROUND: Socioeconomic status (SES) disadvantage shapes exposure to persistent infections and immune aging, but its life-course effects remain understudied. Early adulthood is a crucial period, as immune aging may begin before clinical signs appear. METHODS: Data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) were used to assess SES disadvantage across adolescence (Wave I) and young adulthood (Wave IV). Four life-course SES disadvantage trajectories were defined: non-disadvantaged, upward mobility, downward mobility, and persistent disadvantage. Outcomes included dried blood spot-based seropositivity and IgG antibody levels for Cytomegalovirus (CMV), Herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV), and Helicobacter pylori (H. Pylori) in young adulthood, and DNA-methylation-based CD4⁺ and CD8⁺ memory/naïve and CD4+/CD8+ ratios in early midlife (Wave V). Multivariable regression models evaluated associations between SES trajectories and outcomes. RESULTS: In young adulthood, persistent SES disadvantage was associated with higher odds of CMV, HSV-1, and H. Pylori infection (e.g. H. Pylori OR = 2.2, 95 % CI: 1.7, 2.9) and higher antibody levels (e.g. HSV-1 β = 1.4, 95 % CI: 0.9, 1.9). In early midlife, it was associated with CMV seropositivity and antibody levels (OR = 1.8, 95 % CI: 1.4-2.3; β = 13.0, 95 % CI: 7.4, 18.7), and elevated CD4⁺ and CD8⁺ memory/naïve ratios (e.g. CD4⁺ β = 0.3, 95 % CI: 0.1, 0.5). Associations with upward and downward mobility were weaker and less consistent across outcomes. CONCLUSIONS: Persistent SES disadvantage was consistently associated with higher infection burden and more aged immune cell profiles before midlife. Understanding this link is key for addressing health disparities.