Abstract Body: Introduction: Stark disparities exist in the prevalence of Alzheimer’s disease (AD) and related dementias (ADRD) by social determinants of health (SDoH). Limited research is available on associations of SDoH with AD/ADRD biomarkers. This study aims to assess the impact of SDoH measures on ADRD-associated neuroimaging and plasma biomarkers.
Hypothesis: SDoH measures of area deprivation index (ADI), social vulnerability index (SVI), and environmental justice index (EJI) will be positively associated with poorer ADRD-associated neuroimaging and plasma biomarkers, and cardiometabolic health will partially account for this association.
Methods: This study includes participant data from the Wake Forest Alzheimer’s Disease Research Center from baseline visits. Independent SDoH variables include ADI, SVI, and EJI. Dependent variables include cortical thickness and white matter hyperintensity (WMH) volume, adjusted for intracranial volume, from MRI, and plasma glial fibrillary acidic protein (GFAP) and pTau-181. We conducted bivariate and hierarchical multivariable linear regressions, with demographics (age, sex, education, & cognitive diagnosis) [Model 1], additional adjustment for cardiometabolic health with cardiometabolic index (CMI) [Model 2], and estimated glomerular filtration rate (eGFR) [Model 3; for plasma biomarkers] as covariates.
Results: In bivariate analyses, a significant negative association was observed between ADI and cortical thickness (β=-0.08, p=0.047). No other significant associations were observed. In multivariable analyses (Table 1), EJI was negatively associated with cortical thickness (β=-0.04, p=0.04), and both ADI and SVI were negatively associated with GFAP (β=-0.36, p<0.01 & β=-0.52, p<0.01, respectively), in Model 1. Additionally adjusting for CMI in Model 2, the negative associations of ADI and SVI with GFAP were preserved (β=-0.33, p=0.02 & β=-0.50, p<0.01, respectively). In Model 3, further adjusting for eGFR, ADI remained negatively associated with GFAP (β=-0.37, p=0.03).
Conclusions: Place-based environmental injustice was associated with lower cortical thickness, while neighborhood disadvantage and social vulnerability were associated with higher GFAP levels in adjusted models, suggesting place-based SDoH may be associated with structural brain changes and neuroinflammation. The impact of place-based SDoH needs to be further studied in association with ADRD biomarkers to better understand how we may tackle SDoH among older adults.