Neurology
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Cerebral microbleeds are frequently found in the general elderly population and may reflect underlying vascular disease, but their role in cognitive function is unknown. ⋯ Presence of numerous microbleeds, especially in a strictly lobar location, is associated with worse performance on tests measuring cognitive function, even after adjustments for vascular risk factors and other imaging markers of small vessel disease. These results suggest an independent role for microbleed-associated vasculopathy in cognitive impairment.
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To determine the relationship between β-amyloid (Aβ) load as measured by [(11)C]-Pittsburgh compound B (PiB) PET and cognitive function in cognitively normal older adults. ⋯ There is a modest association between PiB retention and cognitive function in cognitively normal older adults and this relationship between Aβ load and cognitive function is modified by APOE status. Whereas Aβ load is associated with greater cognitive impairment in APOE ε4 carriers, the cognitive function in APOE ε4 noncarriers is influenced less by the Aβ load, suggesting that APOE isoforms modulate the harmful effects of Aβ on cognitive function.
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Cerebral small vessel disease (SVD) is common in aged brains and causes lacunar stroke, diffuse white matter lesions (leukoaraiosis), and vascular cognitive impairment. The pathogenesis is unknown. Endothelial dysfunction is a possible causal factor, and circulating markers of endothelial activation (intercellular adhesion molecule-1, thrombomodulin) and inflammation (interleukin [IL]-6) are elevated in patients with SVD. In this case-control study, we tested whether brain endothelial ICAM1, thrombomodulin, and IL-6 are altered in SVD. ⋯ Our data suggest that cerebral endothelial activation in deep penetrating arteries is not associated with SVD. Endothelial thrombomodulin increased with SVD severity, and CADASIL data suggest that this may be a cerebral response to SVD. Elevated thrombomodulin may be a protective agent in SVD. Our data confirm endothelial involvement in SVD.
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To evaluate the possible role of the default mode network (DMN) in consciousness and assess the diagnostic or prognostic potential of DMN connectivity measures in the assessment of a patient group lacking cognitive awareness. ⋯ The results suggest that the DMN is necessary but not sufficient to support consciousness. Clinically, DMN connectivity may serve as an indicator of the extent of cortical disruption and predict reversible impairments in consciousness.