A - 19 Exploring White Matter Correlates of Fluid Cognitive Functioning in those 85+

Abstract Objective In individuals aged 85+, maintenance of white matter integrity (WMI) is crucial for maintaining communication between brain regions. White matter hyperintensities (WMH), common in aging, are linked with reduced cognitive function. While fluid cognitive functions typically decline with aging, some oldest older adults maintain performance akin to much younger individuals. Methods We examined the relationship between WMI, WMH, and fluid cognitive functioning in individuals aged 85+. WMI and WMH were assessed using two types of MRI imaging and fluid and crystallized cognitive performance were measured using the NIH Toolbox. Cognitive metrics were compared to WMI and WMH. Results Age significantly predicted fluid cognition (β = 0.49, p < 0.05, R^2 = 0.25, p < 0.01). Incorporating white matter measures improved prediction. Notably, cingulate gyrus FA and uncinate fasciculus FA significantly contributed to explained variance (ΔR^2 = 0.12, p < 0.01; ΔR^2 = 0.17, p < 0.01). Splenium corpus callosum MD and fornix column body ad were also significant predictors (ΔR^2 = 0.23, p < 0.01; ΔR^2 = 0.18, p < 0.01).n. Conclusion This study shows the significant impact of age and regional WMI on fluid cognitive function. Age did predict fluid cognition, and consideration of the white matter integrity of the cingulate gyrus and uncinate fasciculus integrity enhanced this association. Further, the integrity of the splenium of the corpus callosum and fornix also played crucial roles. These findings highlight the importance of preservation of white matter health for cognitive well-being in older adults 85 + .