P2–145: Brain white‐matter hyperintensity volume is related to lower cognitive function in older community‐dwelling individuals without cognitive impairment

White matter hyperintensities (WMH) on brain magnetic resonance imaging (MRI) are common in aging, yet their relation to cognition in individuals without overt cognitive impairment is unclear. The aim of this study was to examine the relation of total WMH volume to function in different cognitive systems in older community-dwelling individuals without dementia or mild cognitive impairment. We used data from women and men enrolled in an epidemiologic study of aging, the Memory and Aging Project. Cognitive data included composite measures of five different cognitive systems and global cognition, based on 19 individual tests. Brain MRI data were available in 285 subjects without dementia or mild cognitive impairment (mean age =81 years and education =15 years; 75% women). WMH were automatically segmented based on both T 2 -weighted FLAIR and T 1 -weighted MPRAGE data. Total WMH volume was measured for each participant. Linear regression analyses, adjusted for demographic and other variables, were used to examine the relation of logarithmically-transformed total WMH volume, normalized by intracranial volume, to global cognition and to cognition in five different cognitive domains. Most individuals had some WMH and WMH volume was associated with age (r s =0.41; p <0.001). In a linear regression model adjusted for age, sex, and education, larger WMH volumes were associated with lower levels of global cognitive function (estimate = -0.170, SE =0.057; p =0.003). In a series of adjusted analyses of different cognitive systems, larger WMH volumes were associated with lower perceptual speed (estimate = -0.470, SE =0.094; p <0.001) and semantic memory (estimate = -0.153, SE =0.076; p = 0.046), but not with episodic memory, working memory, or visuospatial abilities (all p >0.14). There was no evidence for effect modification by age, ApoEε4, or vascular disease. This study of older community-dwelling individuals without overt cognitive impairment suggests that total WMH volume is related to lower cognition, especially perceptual speed. Findings appear to be independent of age and vascular disease. Future work will need to examine mechanisms linking WMH to cognition.