Association between inflammation, white matter hyperintensities, and executive function: the role of ethnicity.

Association between inflammation, white matter hyperintensities, and executive function: the role of ethnicity. Frank Brown1, Raul Vintimilla2, James Hall2, Leigh Johnson2, Sid O'Bryant2, for the HABS-HD Study Team. 1University of North Texas 2University of North Texas Health Science Center, Institute for Translational Research Background: Systemic inflammation and cardiovascular risk factors (CVRF) impact neurological health and executive function. Neutrophils produce inflammatory mediators and lymphocytes regulate the inflammatory response. Neutrophil to lymphocyte ratio (NLR) has been used as a marker of systemic inflammation, and as a predictor of cardiovascular health. CVRF are correlated with white matter hyperintensity volume (WMH), an MRI indicator of cerebrovascular health. This study seeks to compare if there is a difference in the association between inflammation (NLR), WMH, and executive function among Mexican Americans and non-Hispanic Whites. Method: We analyzed data from 1083 (505 Mexican Americans and 578 non -Hispanic Whites) cognitively normal participants from the Health and Aging Brain Study (HABS-HD). All participants signed a written consent, and underwent a 3T MRI (Siemens Skyra), clinical labs, clinical evaluation, and cognitive testing. Differential blood cell counts were used to obtain NLR. WMH volume was measured from FLAIR using the Statistical Parametric Mapping (SPM) Lesion Segmentation Tool. Linear regression was used to predict the effect of NLR and Log transformed WMH adjusted for intracranial volume (derived from Freesurferv6.0 analysis of T1 MPRAGE) on Trails B z-score (executive function), and to evaluate if NLR can predict WMH volume. Analysis was split by ethnicity. Age, sex, and education were entered as covariates in the models. Results: Sixty-four percent of the total sample were female. Means for the whole sample were: age 66.02, education years 12.98, Trails B 0.19, WMH volume -0.035, and NLR 2.16. When compared to non-Hispanic Whites, Mexican Americans were significantly younger, less educated, had lower Trails B score, NLR values and WMH volume. NLR predicted Trails B scores (B = -0.14, t =-0.12, p = 0.004) only in Mexican American, while WMH predicted Trails B scores in Mexican American (B = -0.16, t = -3.02, p = 0.003), and Non-Hispanic Whites (B = -0.14, t = -4.33, p < 0.0001). Results remained significant after adjusting for age, sex, education. NLR predicted WMH volume (B = 0.13, t = 3.38, p = 0.001) only in Mexican American. Conclusion: Our findings suggest an association between NLR, WMH and executive function in Mexican Americans. NLR and WMH volume predicted Trails B scores in Mexican Americans. WMH predicted Trails B scores, but there was no association between NLR and executive function in non-Hispanic Whites. These findings demonstrate the importance of race consideration when assessing the relationship between inflammation, CVRF, WMH, and executive function.