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P2‐413: RACIAL DIFFERENCES IN INFLAMMATION, WHITE MATTER MICROSTRUCTURE, AND MYELIN INTEGRITY
Author(s) -
Boots Elizabeth A.,
Castellanos Karla J.,
Deoni Sean C.L.,
Barnes Lisa L.,
Tussing-Humphreys Lisa M.,
Lamar Melissa
Publication year - 2019
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2019.06.2820
Subject(s) - white matter , fractional anisotropy , diffusion mri , medicine , inflammation , myelin , brain size , pathology , cardiology , magnetic resonance imaging , radiology , central nervous system
associations between declining cognitive performance, specifically in attentional control, and b-amyloid (Ab) accumulation. This study examines the anatomical relationship between attentional control and cortical thickness in cognitively normal older adults and investigates whether this relationship is mediated by preclinical AD pathology.Methods: 532 cognitively normal participants (Clinical Dementia Rating 0; mean age1⁄467.3), with cognitive assessments and 3T MRI were recruited from the Knight Alzheimer’s Disease Research Center. Within this cohort, a subset of 413 participants was defined that included participants with a [C]-Pittsburgh Compound B (PIB) or [F]-florbetapir (AV45) Ab PET scan. Values were converted to Centiloid scale for linear regressions. Attentional control was measured using a composite of standardized neuropsychological scores (Stroop, Simon, and task switching). Vertex-wise analysis was performed using a general linear model in the FreeSurfer suite to examine whether attentional control predicts cortical thickness while controlling for age and gender. From the ROI, identified as the significant vertices in the whole group analysis, the average cortical thickness was calculated for each participant. In the subset with Ab PET scans, we examined whether the relationship between the ROI cortical thickness and attentional control was driven by Ab pathology. First we ran a linear model predicting attentional control using both thickness and Ab as predictors. Sobel test was then used to formally assess whether Ab mediates this relationship between thickness and attention. Results: Vertex-wise analysis identified widespread significant associations between attentional control and cortical thickness (Figure 1). When examining the subset, both the ROI thickness (b1⁄43.17, p1⁄41.27e) and Ab (b1⁄4-.007, p1⁄40.0006) significantly predicted attentional control (Figure 2). When formally tested, Ab levels meditated the relationship between thickness and attentional control (indirect effect1⁄40.50, p<0.01; Figure 3). Conclusions: In an older adult population, we found that grey matter integrity is significantly related to attention performance. However, Ab levels partially mediated the relationship between cortical thinning and poor attentional control in cognitively normal older individuals. This signifies preclinical AD is at least partially driving what otherwise would be considered advancing age. nday, July 15, 2019