Cognitive decline

About: Cognitive decline is a research topic. Over the lifetime, 29308 publications have been published within this topic receiving 1174689 citations.

Dark microglia: A new phenotype predominantly associated with pathological states

Abstract: The past decade has witnessed a revolution in our understanding of microglia. These immune cells were shown to actively remodel neuronal circuits, leading to propose new pathogenic mechanisms. To study microglial implication in the loss of synapses, the best pathological correlate of cognitive decline across chronic stress, aging, and diseases, we recently conducted ultrastructural analyses. Our work uncovered the existence of a new microglial phenotype that is rarely present under steady state conditions, in hippocampus, cerebral cortex, amygdala, and hypothalamus, but becomes abundant during chronic stress, aging, fractalkine signaling deficiency (CX3 CR1 knockout mice), and Alzheimer's disease pathology (APP-PS1 mice). Even though these cells display ultrastructural features of microglia, they are strikingly distinct from the other phenotypes described so far at the ultrastructural level. They exhibit several signs of oxidative stress, including a condensed, electron-dense cytoplasm and nucleoplasm making them as "dark" as mitochondria, accompanied by a pronounced remodeling of their nuclear chromatin. Dark microglia appear to be much more active than the normal microglia, reaching for synaptic clefts, while extensively encircling axon terminals and dendritic spines with their highly ramified and thin processes. They stain for the myeloid cell markers IBA1 and GFP (in CX3 CR1-GFP mice), and strongly express CD11b and microglia-specific 4D4 in their processes encircling synaptic elements, and TREM2 when they associate with amyloid plaques. Overall, these findings suggest that dark microglia, a new phenotype that we identified based on their unique properties, could play a significant role in the pathological remodeling of neuronal circuits, especially at synapses.

Decreased functional connectivity by aging is associated with cognitive decline

Abstract: Aging is related to cognitive decline, and it has been reported that aging disrupts some resting state brain networks. However, most studies have focused on the default mode network and ignored other resting state networks. In this study, we measured resting state activity using fMRI and explored whether cognitive decline with aging is related to disrupted resting state networks. Independent component analysis was used to evaluate functional connectivity. Notably, the connectivity within the salience network that consisted of the bilateral insula and the anterior cingulated cortex decreased with aging; the impairment of functional connectivity was correlated with measured decreases in individual cognitive abilities. Furthermore, certain internetwork connectivities (salience to auditory, default mode to visual, etc.) also decreased with aging. These results suggest that (1) aging affects not only the default mode network but also other networks, specifically the salience network; (2) aging affects internetwork connectivity; and (3) disruption of the salience network is related to cognitive decline in elderly people.

IANA task force on nutrition and cognitive decline with aging.

Abstract: Cognitive impairment can be influenced by a number of factors The potential effect of nutrition has become a topic of increasing scientific and public interest In particular, there are arguments that nutrients (food and/or supplements) such as vitamins, trace minerals, lipids, can affect the risk of cognitive decline and dementia, especially in frail elderly people at risk of deficiencies Our objective in this paper is to review data relating diet to risk of cognitive decline and dementia, especially Alzheimer's disease (AD) We chose to focus our statements on homocysteine-related vitamins (B-vitamins), antioxidant nutrients (vitamins E and C, carotenoids, flavonoids, enzymatic cofactors) and dietary lipids Results of epidemiological studies may sometimes appeared conflicting; however, certain associations are frequently found High intake of saturated and trans-unsaturated (hydrogenated) fats were positively associated with increased risk of AD, whereas intake of polyunsaturated and monounsaturated fats were protective against cognitive decline in the elderly in prospective studies Fish consumption has been associated with lower risk of AD in longitudinal cohort studies Moreover, epidemiologic data suggest a protective role of the B-vitamins, especially vitamins B9 and B12, on cognitive decline and dementia Finally, the results on antioxidant nutrients may suggest the importance of having a balanced combination of several antioxidant nutrients to exert a significant effect on the prevention of cognitive decline and dementia, while taking into account the potential adverse effects of these nutrients There is no lack of attractive hypotheses to support research on the relationships between nutrition and cognitive decline It is important to stress the need to develop further prospective studies of sufficiently long duration, including subjects whose diet is monitored at a sufficiently early stage or at least before disease or cognitive decline exist Meta analyses should be developed, and on the basis of their results the most appropriate interventional studies can be planned These studies must control for the greatest number of known confounding factors and take into account the impact of the standard social determinants of food habits, such as the regional cultures, social status, and educational level