Axon–glial disruption: the link between vascular disease and Alzheimer's disease?

2011 ◽  
Vol 39 (4) ◽  
pp. 881-885 ◽  
Author(s):  
Karen Horsburgh ◽  
Michell M. Reimer ◽  
Philip Holland ◽  
Guiquan Chen ◽  
Gillian Scullion ◽  
...  

Vascular risk factors play a critical role in the development of cognitive decline and AD (Alzheimer's disease), during aging, and often result in chronic cerebral hypoperfusion. The neurobiological link between hypoperfusion and cognitive decline is not yet defined, but is proposed to involve damage to the brain's white matter. In a newly developed mouse model, hypoperfusion, in isolation, produces a slowly developing and diffuse damage to myelinated axons, which is widespread in the brain, and is associated with a selective impairment in working memory. Cerebral hypoperfusion, an early event in AD, has also been shown to be associated with white matter damage and notably an accumulation of amyloid. The present review highlights some of the published data linking white matter disruption to aging and AD as a result of vascular dysfunction. A model is proposed by which chronic cerebral hypoperfusion, as a result of vascular factors, results in both the generation and accumulation of amyloid and injury to white matter integrity, resulting in cognitive impairment. The generation of amyloid and accumulation in the vasculature may act to perpetuate further vascular dysfunction and accelerate white matter pathology, and as a consequence grey matter pathology and cognitive decline.

2016 ◽  
Vol 52 (4) ◽  
pp. 1311-1319 ◽  
Author(s):  
Yun Zhai ◽  
Toru Yamashita ◽  
Yumiko Nakano ◽  
Zhuoran Sun ◽  
Ryuta Morihara ◽  
...  

2020 ◽  
Vol 10 (2) ◽  
Author(s):  
Anil Kumar S ◽  
Saif SA ◽  
Oothuman P ◽  
Mustafa MIA

Introduction: Reduced cerebral blood fl ow is associated with neurodegenerative disorders and dementia, in particular. Experimental evidence has demonstrated the initiating role of chronic cerebral hypoperfusion in neuronal damage to the hippocampus, the cerebral cortex, the white matter areas and the visual system. Permanent, bilateral occlusion of the common carotid arteries of rats (two vessel occlusion - 2VO) has been introduced for the reproduction of chronic cerebral hypoperfusion as it occurs in Alzheimer’s disease and human aging. Increased generation of free radicals through lipid peroxidation can damage neuronal cell membrane. Markers of lipid peroxidation have been found to be elevated in brain tissues and body fl uids in neurodegenerative diseases, including Alzheimer’s disease, Parkinson disease and amyotrophic lateral sclerosis. Materials and Methods: Malondialdehyde (MDA), final product of lipid peroxidation, was estimated by thiobarbituric acid-reactive substances (TBARS) assay kit at eight weeks after induction of 2VO in the rats and control group. Results: Our study revealed a highly signifi cant (p<0.001) increase in the mean MDA concentration (12.296 ± 1.113 μM) in 2VO rats as compared to the control group (5.286 ± 0.363 μM) rats. Conclusion: Therapeutic strategies to modulate lipid peroxidation early throughout the course of the disease may be promising in slowing or possibly preventing neurodegenerative disorders.


Author(s):  
Francis Cambronero ◽  
Angela L. Jefferson

Hemodynamic impairment is a prominent feature in aging, vascular cognitive impairment and dementia, and Alzheimer’s disease, including patterned changes in cerebral blood flow (CBF) that can be detected prior to concomitant pathologies. These CBF abnormalities drive vascular dysfunction through a variety of biological pathways and ultimately contribute to cerebrovascular disease associated with cognitive impairment. Importantly, the co-existence of cerebrovascular disease and Alzheimer’s disease is exceedingly common and worsens the progression of clinical symptoms, likely through accelerating neurotoxic protein deposition and the loss of cerebrovascular integrity. Emerging evidence further suggests that the brain may be more susceptible to subclinical cardiovascular dysfunction in aging adults, particularly since the accumulation of cardiovascular risk factors over the lifespan creates a more vulnerable vascular system. Although age-associated CBF dysregulation has varied and complex origins, it undoubtedly serves a critical role in the early progression of neurodegenerative disease and may help explain the considerable overlap between the most common clinical dementias.


2020 ◽  
pp. 0271678X2096892
Author(s):  
Tian Feng ◽  
Toru Yamashita ◽  
Ryo Sasaki ◽  
Koh Tadokoro ◽  
Namiko Matsumoto ◽  
...  

White matter lesions (WMLs) caused by cerebral chronic hypoperfusion (CCH) may contribute to the pathophysiology of Alzheimer’s disease (AD). However, the underlying mechanisms and therapeutic approaches have yet to be totally identified. In the present study, we investigated a potential therapeutic effect of the free radical scavenger edaravone (EDA) on WMLs in our previously reported novel mouse model of AD (APP23) plus CCH with motor and cognitive deficits. Relative to AD with CCH mice at 12 months (M) of age, EDA strongly improved CCH-induced WMLs in the corpus callosum of APP23 mice at 12 M by improving the disruption of white matter integrity, enhancing the proliferation of oligodendrocyte progenitor cells, attenuating endothelium/astrocyte unit dysfunction, and reducing neuroinflammation and oxidative stress. The present study demonstrates that the long-term administration of EDA may provide a promising therapeutic approach for WMLs in AD plus CCH disease with cognitive deficits.


2013 ◽  
Vol 9 ◽  
pp. P701-P701
Author(s):  
Margit Mikula ◽  
Petroula Proitsi ◽  
Martina Sattlecker ◽  
Mike O'Sullivan ◽  
Andy Simmons ◽  
...  

2020 ◽  
Author(s):  
Mahsa Dadar ◽  
Richard Camicioli ◽  
Simon Duchesne ◽  
D. Louis Collins ◽  

ABSTRACTINTRODUCTIONCognitive decline in Alzheimer’s disease is associated with amyloid-β accumulation, neurodegeneration and cerebral small vessel disease, but the temporal relationships between these factors is not well established.METHODSData included white matter hyperintensity (WMH) load, grey matter (GM) atrophy and Alzheimer’s Disease Assessment Scale-Cognitive-Plus (ADAS13) scores for 720 participants and cerebrospinal fluid amyloid (Aβ1-42) for 461 participants from the Alzheimer’s Disease Neuroimaging Initiative. Linear regressions were used to assess the relationships between baseline WMH, GM, and Aβ1-42 to changes in WMH, GM, Aβ1-42, and cognition at one-year follow-up.RESULTSBaseline WMHs and Aβ1-42 predicted WMH increase and GM atrophy. Baseline WMHs, GM, and Aβ1-42 predicted worsening cognition. Only baseline Aβ1-42 predicted change in Aβ1-42.DISCUSSIONBaseline WMHs lead to greater future GM atrophy and cognitive decline, suggesting that WM damage precedes neurodegeneration and cognitive decline. Baseline Aβ1-42 predicted WMH increase, suggesting a potential role of amyloid in WM damage.Research in ContextSystematic Review: Both amyloid β and neurodegeneration are primary pathologies in Alzheimer’s disease. White matter hyperintensities (indicative of presence of cerebrovascular disease) might also be part of the pathological changes in Alzheimer’s. However, the temporal relationship between white matter hyperintensities, amyloid β, neurodegeneration, and cognitive decline is still unclear.Interpretation: Our results establish a potential temporal order between white matter hyperintensities, amyloid β, neurodegeneration, and cognitive decline, showing that white matter hyperintensities precede neurodegeneration and cognitive decline. The results provide some evidence that amyloid β deposition, in turn, precedes accumulation of white matter hyperintensities.Future Directions: The current findings reinforce the need for future longitudinal investigations of the mechanisms through which white matter hyperintensities impact the aging population in general and Alzheimer’s disease patients, in particular.


Author(s):  
Kirsty E. McAleese ◽  
Mohi Miah ◽  
Sophie Graham ◽  
Georgina M. Hadfield ◽  
Lauren Walker ◽  
...  

AbstractCerebral white matter lesions (WML) encompass axonal loss and demyelination and are assumed to be associated with small vessel disease (SVD)-related ischaemia. However, our previous study in the parietal lobe white matter revealed that WML in Alzheimer’s disease (AD) are linked with degenerative axonal loss secondary to the deposition of cortical AD pathology. Furthermore, neuroimaging data suggest that pathomechanisms for the development of WML differ between anterior and posterior lobes with AD-associated degenerative mechanism driving posterior white matter disruption, and both AD-associated degenerative and vascular mechanisms contributed to anterior matter disruption. In this pilot study, we used human post-mortem brain tissue to investigate the composition and aetiology of frontal WML from AD and non-demented controls to determine if frontal WML are SVD-associated and to reveal any regional differences in the pathogenesis of WML. Frontal WML tissue sections from 40 human post-mortem brains (AD, n = 19; controls, n = 21) were quantitatively assessed for demyelination, axonal loss, cortical hyperphosphorylated tau (HPτ) and amyloid-beta (Aβ) burden, and arteriolosclerosis as a measure of SVD. Biochemical assessment included Wallerian degeneration-associated protease calpain and the myelin-associated glycoprotein to proteolipid protein ratio as a measure of ante-mortem ischaemia. Arteriolosclerosis severity was found to be associated with and a significant predictor of frontal WML severity in both AD and non-demented controls. Interesting, frontal axonal loss was also associated with HPτ and calpain levels were associated with increasing Aβ burden in the AD group, suggestive of an additional degenerative influence. To conclude, this pilot data suggest that frontal WML in AD may result from both increased arteriolosclerosis and AD-associated degenerative changes. These preliminary findings in combination with previously published data tentatively indicate regional differences in the aetiology of WML in AD, which should be considered in the clinical diagnosis of dementia subtypes: posterior WML maybe associated with degenerative mechanisms secondary to AD pathology, while anterior WML could be associated with both SVD-associated and degenerative mechanisms.


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