Objective, Relative, and Subjective Measures of Socioeconomic Status and White Matter Hyperintensities: A Cross-sectional Analysis in Midlife Adults

OBJECTIVE: Lower socioeconomic status (SES) is associated with adverse health outcomes, including poor brain health and greater white matter hyperintensity (WMH) volume. Traditional SES measures may not fully capture the socioeconomic experience. This study examined associations between three SES indicators and WMH volume in a healthy, midlife adult sample. METHODS: In data from participants of the Neurobiology of Adult Health (NOAH) Project who underwent high-resolution 7T MRI, we estimated the association between three SES measures: household income; income relative to neighborhood average; and subjective SES with WMH volumes. We fit linear regression models estimating associations between SES and log-transformed WMHs, controlling for age, race, ethnicity, and household size. We tested effect measure modification by sex using its interaction with SES measures. We investigated whether subclinical cardiovascular disease or cardiovascular risk mediated these associations. RESULTS: Participants (N=189) were aged 28-56 (60% female). Neither absolute nor relative household income was associated with WMH volume. However, a significant interaction emerged between subjective SES and sex (β=-0.26, 95% CI: -0.44 to -0.08), indicating that lower subjective SES was associated with greater WMH volume in female but not male participants. We found no significant mediators. CONCLUSIONS: Subjective SES may be a more sensitive predictor of brain health in midlife than other SES measures, particularly for female participants. Sex differences in WMH burden and SES-health associations may reflect factors not captured in traditional models. This study highlights the value of incorporating multiple contextual SES measures and considering sex differences when assessing neurocognitive risk.