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Publications

Journal Article Epublish

PubMed: 39003383 DOI: 10.1038/s43856-024-00569-w

The mediating role of systemic inflammation and moderating role of racialization in disparities in incident dementia.

Commun Med (Lond) 4(1):142

Authors: César Higgins Tejera, Erin B Ware, Margaret T Hicken, Lindsay C Kobayashi, Herong Wang, Freida Blostein, Matthew Zawistowski, Bhramar Mukherjee, Kelly M Bakulski

Affiliations

  • School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA.
  • Department of Neurology, Division of Neuroimmunology and Neurological Infections, Johns Hopkins University, 600 N Wolfe St, Baltimore, MD, 21287, USA.
  • Institute for Social Research, University of Michigan, 426 Thompson St, 48104, Ann Arbor, MI, USA.
  • School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA.
  • Vanderbilt University, 2525 West End Avenue, 37203, Nashville, TN, USA.

Abstract

BACKGROUND

Exposure to systemic racism is linked to increased dementia burden. To assess systemic inflammation as a potential pathway linking exposure to racism and dementia disparities, we investigated the mediating role of C-reactive protein (CRP), a systemic inflammation marker, and the moderating role of the racialization process in incident dementia.

METHODS

In the US Health and Retirement Study (n = 6,908), serum CRP was measured at baseline (2006, 2008 waves). Incident dementia was classified by cognitive tests over a six-year follow-up. Self-reported racialized categories were a proxy for exposure to the racialization process. We decomposed racialized disparities in dementia incidence (non-Hispanic Black and/or Hispanic vs. non-Hispanic white) into 1) the mediated effect of CRP, 2) the moderated portion attributable to the interaction between racialized group membership and CRP, and 3) the controlled direct effect (other pathways through which racism operates).

RESULTS

The 6-year cumulative incidence of dementia is 12%. Among minoritized participants (i.e., non-Hispanic Black and/or Hispanic), high CRP levels ( ≥ 75 th percentile or 4.73μg/mL) are associated with 1.26 (95%CI: 0.98, 1.62) times greater risk of incident dementia than low CRP ( < 4.73μg/mL). Decomposition analysis comparing minoritized versus non-Hispanic white participants shows that the mediating effect of CRP accounts for 3% (95% CI: 0%, 6%) of the racial disparity, while the interaction effect between minoritized group status and high CRP accounts for 14% (95% CI: 1%, 27%) of the disparity. Findings are robust to potential violations of causal mediation assumptions.

CONCLUSIONS

Minoritized group membership modifies the relationship between systemic inflammation and incident dementia.

MeSH

Dementia, Incidence, C-Reactive Protein, Racism