Background: Despite convenience, accessibility, and strong correlation to severity of Alzheimer

Background-In the diagnosis of Alzheimer's disease, structural MRI scans have been used primarily to exclude non-Alzheimer's cause of dementia. However, the pattern and extent of medial temporal atrophy (MTA) on structural MRI scans, which correlates strongly with the pathological severity of Alzheimer's disease (AD), can be used to support the diagnosis of a degenerative dementia, especially AD, even in its early pre-dementia stage.

Background The traditional consensus diagnosis (ConsDx) of normal cognition, mild cognitive impairment (MCI), and dementia relies on the reconciliation of an informant-based report of cognitive and functional impairment by a physician (PhyDx), and a neuropsychological diagnosis (NPDx). As this procedure may be labor-intensive and influenced by the philosophy and biases of a clinician, the diagnostic algorithm (AlgDx) was developed to identify individuals as cognitively normal, with MCI or dementia. Methods The AlgDx combines the PhyDx with the NPDx, using a computational algorithm that provides cognitive diagnoses, as defined by the National Alzheimer Coordinating Center/Uniform Data Set (NACC/UDS) nomenclature. Reliability of the AlgDx was assessed in 532 community-dwelling elderly subjects by its concordance with the ConsDx, and association with two biomarkers, medial temporal atrophy (MTA) scores of brain MRI scans, and ApoE-ε4 genotype. Results A high degree of concordance was observed between ConsDx and AlgDx with a weighted Cohen’s kappa of 0.84. Concordance of the AlgDx to the same ConsDx categories ranged from 85% to 92%. Excellent discriminative validity was observed as AlgDx, MTA scores, and APOE-ε4 allele frequencies distinguished amnestic MCI and dementia subjects from normal subjects. Conclusion The AlgDx of normal cognition, MCI, and dementia is a valid alternative that reduces time, effort and biases associated with the ConsDx. The inherent reliability of a fixed algorithm, together with its efficiency and avoidance of individual bias, suggests the AlgDx may be used in longitudinal, multi-site clinical trials and population studies of MCI and dementia.

BACKGROUND AND PURPOSE:White matter hyperintensities (WMHs) are frequently characterized as markers of cerebrovascular disease, whereas medial temporal atrophy (MTA) is a recognized marker of Alzheimer disease (AD). Our purpose was to test the reliability of a visual rating system (VRS) in evaluating WMHs and MTA and in distinguishing healthy from cognitively impaired subjects.

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