CEREBRAL MICROBLEEDS ARE ASSOCIATED WITH CEREBRAL BLOOD FLOW AND METABOLISM BUT NOT AMYLOID BURDEN OR BRAIN ATROPHY IN COGNITIVELY NORMAL ELDERLY

in AD, as well as the connectivity of the DMN. In this study, we aimed to analyze the extent in which damage in the DMN white matter influences in cognitive function in MCI and AD patients compared to healthy elderly. Methods:We studied 76 subjects (25 mild AD, 21 amnestic Mild Cognitive Impairment subjects and 30 controls). MRI data were acquired on a 3.0T MRI Philips Achieva scanner. Tensor calculation and tractographywere performed with ExploreDTI software, and axial diffusivity, radial diffusivity, fractional anisotropy, mean diffusivity and streamline count were calculated. Participants also underwent a full range neuropsychological testing. For differences between groups, we performed ANOVA with Tukey posthoc test (adjusting for multiple comparisons). In order to verify if there was any association between cognition and DTI parameters, we performed a multiple stepwise regression, adjusted for multiple comparisons. For streamline count, we used white matter total volume as a covariate.Results: AD patients showed lower values of fractional anisotropy and radial diffusivity in the cingulum (P1⁄4.010 and .012, respectively), and lower radial diffusivity in the parahippocampal bundle (P1⁄4.013) compared to controls. R egression models revealed that cognitive performance is accounted for by 30% of white matter microstructural values, together with years of education. Conclusions: Only AD patients differed from controls in terms of DTI values between DMN nodes. DTI measures have a relative strong predicting power in cognitive performance, together with years of education.