Current Alzheimer research
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Multicenter Study Observational Study
Functional Activities Questionnaire Items that Best Discriminate and Predict Progression from Clinically Normal to Mild Cognitive Impairment.
Impairment in instrumental activities of daily living (IADL) emerges in the transition from mild cognitive impairment (MCI) to Alzheimer's disease (AD) dementia. Some IADL scales are sensitive to early deficits in MCI, but none have been validated for detecting subtle functional changes in clinically normal (CN) elderly at risk for AD. ⋯ These results demonstrate that certain questions are especially sensitive in detecting the earliest functional changes in CN elderly at risk for AD. As the field moves toward earlier intervention in preclinical AD, it is important to determine which IADL changes can be detected at that stage and track decline over time.
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Alzheimer's disease (AD) is the most common neurodegenerative disorder pathologically characterized by amyloid-beta (Aβ) plaques and neurofibrillary tangles. The aggregation of Aβ precedes tau pathologies in AD; however, the causal relation between the two pathologies and the mechanisms by which aggregated forms of Aβ contribute to cortical thinning are not fully understood. We proposed quantitative Aβ-weighted cortical thickness analysis to investigate the regional relationship between cortical thinning and amyloid plaque deposition using magnetic resonance (MR) and Pittsburg Compound B (PiB) positron emission tomography (PET) images in patients with AD, mild cognitive impairment (MCI), and subjects with normal cognition. ⋯ Classification models that used Aβ-weighted cortical thickness were not inferior to classification models that used only cortical thickness or amyloid deposition. In addition, based on timing of changes in cortical thinning and Aβ deposition such as Aβ deposition after cortical thinning; cortical thinning after Aβ deposition, or concurrent Aβ deposition and cortical thinning, we identified three types of relationships between cortical thinning and Aβ deposition: (1) Aβ-associated cortical thinning; (2) Aβ-independent cortical thinning; and (3) Aβ deposition only without cortical thinning. Taken together, these findings suggest that Aβ-weighted cortical thickness values can be used as an objective biomarker of structural changes caused by amyloid pathology in the brain.
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The β-secretase enzyme BACE1, which initiates the cleavage of amyloid precursor protein (APP) into the amyloid-β (Aβ) peptide, is a prime therapeutic target for Alzheimer's disease (AD). However, recent investigations using genetic animal models raise concern that therapeutic BACE1 inhibition may encounter the dramatic reduction of efficacy in ameliorating AD-like pathology and memory deficits during disease progression. Here, we compared the effects of the potent and selective small-molecule BACE1 inhibitor GRL-8234 in different pathological stages of AD mouse model. ⋯ In contrast, only marginal reductions of Aβ42 were observed in 12-month-old 5XFAD mice treated with GRL-8234 and their memory function remained impaired. We found that not only BACE1 but also full-length APP expression was significantly elevated with progressive Aβ accumulation in 5XFAD mice, while GRL-8234 failed to affect these detrimental mechanisms that further accelerate plaque growth in brains of older 5XFAD mice. Therefore, our results provide important insights into the mechanisms by which Aβ accumulation and related memory impairments become less responsive to rescue by BACE1 inhibition during the course of AD development.