Journal of Alzheimer's disease : JAD
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Intracerebroventricular (icv) streptozotocin (STZ) administration induces pathological and behavioral alterations similar to those observed in Alzheimer's disease (AD) and is thus considered an experimental model of sporadic AD. Since caffeine (an adenosine receptor antagonist) and selective antagonists of adenosine A2A receptors modify the course of memory impairment in different amyloid-β-based experimental models of AD, we now tested the impact of caffeine on STZ-induced dementia and associated neurodegeneration in the hippocampus as well as on the expression and density of adenosine receptors. ⋯ Caffeine consumption (1 g/L in the drinking water starting 2 weeks before the STZ challenge) prevented the STZ-induced memory impairment and neurodegeneration as well as the upregulation of A2AR. These findings provide the first demonstration that caffeine prevents sporadic dementia and implicate the control of central A2AR as its likely mechanism of action.
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β-Asarone, an active component of the Acori graminei rhizome that has been used as traditional Chinese herb, has been reported to be capable of inhibiting neuronal apoptosis. However, the signaling mechanism underlying the inhibitory effect of β-asarone has remained elusive. This study was aimed to investigate whether the CaMKII signaling pathway is involved in the β-asarone mediated neuroprotection. ⋯ A significant increase in CaMKII/CREB/Bcl-2 expression was observed in the cortex of the AβPP/PS1 mice treated with β-asarone. In summary, our observations demonstrated that β-asarone can inhibit neuronal apoptosis via the CaMKII/CREB/Bcl-2 signaling pathway in in vitro models and in AβPP/PS1 mice. Therefore, β-asarone can be used as a potential therapeutic agent in the long-term treatment of Alzheimer's disease.
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Significant differences exist in demographic characteristics between responders and non-responders in population-based studies on mental health and cognitive status, but much less is known regarding differences in the prevalence of dementia and cognitive dysfunction between them. Here we compared the prevalence of dementia and mild cognitive impairment between early responders of a mass brain function examination and delayed responders (non-responders of the mass brain function examination) in a survey of elderly Japanese citizens (≥65 years) to evaluate non-responder bias. All residents in an area of Nakajima, Japan, were considered as potential candidates (n = 783). ⋯ Delayed responders (n = 320) were significantly older and less educated than the early responders (n = 307). The delayed responders also exhibited a higher frequency of dementia and mild cognitive impairment than the early responders, even when the groups were restricted to the age group 65-89 years. Our results suggest that population-based studies likely underestimate the prevalence of dementia and mild cognitive impairment, especially if the participation rate is low.
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To date, the exact pathogenesis of dementia is still unknown. The most frequently hypothesized initiating factor is an accumulation of the protein amyloid-β in the brain, which has been associated with dementia of the Alzheimer type. Another potentially important initiating factor is a disrupted blood-brain barrier. ⋯ Although amyloid-β and blood-brain barrier dysfunction have both been associated with one particular type of dementia (Alzheimer's disease and vascular dementia, respectively), they co-exist in most demented patients. In fact, increasing evidence indicates that amyloid-β and blood-brain barrier disruption may interact and facilitate each other in their effect on neurodegeneration. The present systematic analysis describes the available evidence for a significant interplay between amyloid-β and blood-brain barrier function in dementia.
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Many cognitive screening instruments have been developed during the last decades to detect mild cognitive dysfunction and dementia, and there is an ongoing discussion as to which tool should be used in which setting and which challenges have to be considered. Among other aspects, dependence on age is a recognized problem in screening tools which still has not found its way into common scoring procedures. Another aspect which has been handled very heterogeneously is which domain is represented in which proportion in the total score. ⋯ In this review, four cognitive screening tools that all follow a common, stringent concept and pay regard to some critical aspects are described: the DemTect, a "generic" tool; the PANDA for Parkinson's disease patients; the EASY, a non-verbal, culture-fair screening test for patients with migration background; and the MUSIC for patients with multiple sclerosis. All of these screening instruments have an age-correction, provide a total score in which the different subtests are weighted according to their individual sensitivity and specificity, and include tasks that are specifically aligned to the cognitive profile of the target group, including the EASY with non-verbal, culture-fair tasks to overcome language and cultural barriers. The development, main characteristics, data, and limitations of these tools are presented and discussed against the background of the current landscape of cognitive screening tools.