Journal of Alzheimer's disease : JAD
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Traumatic brain injury (TBI) is the most established environmental risk factor for Alzheimer's disease (AD), but it is unclear if TBI is specifically associated with early-onset AD (EOAD). ⋯ These findings suggest, but do not establish, that TBI is a specific risk factor for EOAD and may lead to disinhibition, a feature that often results from the frontal effects of head injury. This study recommends further research on the effects of TBI in EOAD in larger numbers of participants.
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The purpose of this explorative study was to investigate whether diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameter changes are reliable measures of white matter integrity changes in Alzheimer's disease (AD) patients using a whole brain voxel-based analysis (VBA). Therefore, age- and gender-matched patients with mild cognitive impairment (MCI) due to AD (n = 18), dementia due to AD (n = 19), and age-matched cognitively healthy controls (n = 14) were prospectively included. The magnetic resonance imaging protocol included routine structural brain imaging and DKI. ⋯ Groups were compared using VBA. Differences in diffusion and mean kurtosis measures between MCI and AD patients and controls were shown, and were mainly found in the splenium of the corpus callosum and the corona radiata. Hence, DTI and DKI parameter changes are suggestive of white matter changes in AD.
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Case Reports
Alzheimer's Disease FDG PET Imaging Pattern in an Amyloid-Negative Mild Cognitive Impairment Subject.
The revised NIA-AA diagnostic criteria for Alzheimer's disease (AD) and mild cognitive impairment (MCI) due to AD make use of amyloid pathology and neurodegeneration biomarkers which increase the diagnostic confidence in the majority of patients. However, in daily praxis, cases with conflicting biomarker constellations occur. ⋯ In this subject, the biomarkers of Aβ deposition were negative. [18F]FDG PET, however, showed an AD-typical hypometabolism. Further studies are required to determine frequency and relevance of cases with neurodegeneration-first biomarker constellations to improve our understanding on pathogenesis and diagnosis of AD.
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Comparative Study
Mirror Image of the Amyloid-β Species in Cerebrospinal Fluid and Cerebral Amyloid in Alzheimer's Disease.
Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) accumulation in brain that is paralleled by Aβ(1-42) reduction in cerebrospinal fluid (CSF). We analyzed the pattern of Aβ peptides, including the N- and C-terminal truncated fragments, in brain and CSF from two familial and one sporadic AD cases. We found that (i) each patient is characterized by a distinct Aβ profile in CSF and brain deposits and (ii) the CSF Aβ pattern mirrors the Aβ profile of cerebral amyloid. These results suggest the existence of different molecular AD subtypes which can be recognized by CSF analysis, enabling patient stratification.
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There is growing evidence that the human brain is a large scale complex network. The structural network is reported to be disrupted in cognitively impaired patients. However, there have been few studies evaluating the effects of amyloid and small vessel disease (SVD) markers, the common causes of cognitive impairment, on structural networks. ⋯ Greater white matter hyperintensity volumes or lacunae numbers were significantly associated with decreased network integration (increased shortest path length, decreased global efficiency) and increased network segregation (increased clustering coefficient, increased transitivity, increased modularity). Decreased network integration or increased network segregation were associated with poor performances in attention, language, visuospatial, memory, and frontal-executive functions. Our results suggest that SVD alters white matter network integration and segregation, which further predicts cognitive dysfunction.