Associations between socioeconomic position index and epigenetic aging in NHANES

Lower socioeconomic position (SEP) is related to poor health, and epigenetic aging represents a potential mechanism of action. We aimed to estimate associations between a novel measure of SEP and epigenetic age in a nationally representative cohort. We used data from NHANES survey waves 1999-2000 and 2001-2002. Our exposure was a novel three-category indicator of SEP, incorporating income, wealth, occupational status, and educational attainment. Our outcomes included 13 different epigenetic clocks and leukocyte telomere length. Higher SEP was associated with lower epigenetic age acceleration for a subset of epigenetic clocks tested. In adjusted models, higher (vs. lower) SEP was associated with lower epigenetic age for the GrimAgeMort (β [95% CI] = -0.94 [-1.84, -0.05]), GrimAge2Mort (β [95% CI] = -1.22 [-2.26, -0.18]), and HorvathTelo (β [95% CI] = 0.07 [0.01, 0.13]) epigenetic clocks. Higher SEP was associated with greater telomere length, though CI contained the null (β [95% CI] = 0.04 [-0.01, 0.09]). The magnitude of association was larger for men vs. women (p-value for interactions for GrimAgeMort and GrimAge2Mort < 0.05), though 95% CIs overlapped (GrimAgeMort β [95% CI] men: -2.01 [-3.18, -0.84], women: -0.31 [-1.39, 0.77], GrimAge2Mort -2.42 [-3.91, -0.94], women: -0.52 [-1.70, 0.66]). Most associations remained stable, though CI for most estimates contained the null, after adjustment for cell proportions. In this cross-sectional analysis, higher SEP was associated with lower epigenetic age acceleration for a limited number of epigenetic clocks, and associations were null controlling for cell proportions. Future work should examine whether cell composition mediates these associations.