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Nehra G, Bauer B, Hartz AMS. Blood-brain barrier leakage in Alzheimer's disease: From discovery to clinical relevance. Pharmacol Ther 2022; 234:108119. [PMID: 35108575 DOI: 10.1016/j.pharmthera.2022.108119] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia. AD brain pathology starts decades before the onset of clinical symptoms. One early pathological hallmark is blood-brain barrier dysfunction characterized by barrier leakage and associated with cognitive decline. In this review, we summarize the existing literature on the extent and clinical relevance of barrier leakage in AD. First, we focus on AD animal models and their susceptibility to barrier leakage based on age and genetic background. Second, we re-examine barrier dysfunction in clinical and postmortem studies, summarize changes that lead to barrier leakage in patients and highlight the clinical relevance of barrier leakage in AD. Third, we summarize signaling mechanisms that link barrier leakage to neurodegeneration and cognitive decline in AD. Finally, we discuss clinical relevance and potential therapeutic strategies and provide future perspectives on investigating barrier leakage in AD. Identifying mechanistic steps underlying barrier leakage has the potential to unravel new targets that can be used to develop novel therapeutic strategies to repair barrier leakage and slow cognitive decline in AD and AD-related dementias.
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Yates PA, Villemagne VL, Ellis KA, Desmond PM, Masters CL, Rowe CC. Cerebral microbleeds: a review of clinical, genetic, and neuroimaging associations. Front Neurol 2014; 4:205. [PMID: 24432010 PMCID: PMC3881231 DOI: 10.3389/fneur.2013.00205] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/06/2013] [Indexed: 12/14/2022] Open
Abstract
Cerebral microbleeds (microbleeds) are small, punctuate hypointense lesions seen in T2* Gradient-Recall Echo (GRE) and Susceptibility-Weighted (SWI) Magnetic Resonance Imaging (MRI) sequences, corresponding to areas of hemosiderin breakdown products from prior microscopic hemorrhages. They occur in the setting of impaired small vessel integrity, commonly due to either hypertensive vasculopathy or cerebral amyloid angiopathy. Microbleeds are more prevalent in individuals with Alzheimer’s disease (AD) dementia and in those with both ischemic and hemorrhagic stroke. However they are also found in asymptomatic individuals, with increasing prevalence with age, particularly in carriers of the Apolipoprotein (APOE) ε4 allele. Other neuroimaging findings that have been linked with microbleeds include lacunar infarcts and white matter hyperintensities on MRI, and increased cerebral β-amyloid burden using 11C-PiB Positron Emission Tomography. The presence of microbleeds has been suggested to confer increased risk of incident intracerebral hemorrhage – particularly in the setting of anticoagulation – and of complications of immunotherapy for AD. Prospective data regarding the natural history and sequelae of microbleeds are currently limited, however there is a growing evidence base that will serve to inform clinical decision-making in the future.
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Affiliation(s)
- Paul A Yates
- Department of Nuclear Medicine and Centre for PET, Austin Health , Heidelberg, VIC , Australia ; Department of Medicine, The University of Melbourne , Parkville, VIC , Australia
| | - Victor L Villemagne
- Department of Nuclear Medicine and Centre for PET, Austin Health , Heidelberg, VIC , Australia ; Department of Medicine, The University of Melbourne , Parkville, VIC , Australia ; Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville, VIC , Australia
| | - Kathryn A Ellis
- Department of Medicine, The University of Melbourne , Parkville, VIC , Australia ; Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville, VIC , Australia
| | - Patricia M Desmond
- Department of Medicine, The University of Melbourne , Parkville, VIC , Australia ; Department of Radiology, Royal Melbourne Hospital , Parkville, VIC , Australia
| | - Colin L Masters
- Department of Medicine, The University of Melbourne , Parkville, VIC , Australia ; Florey Institute of Neuroscience and Mental Health, University of Melbourne , Parkville, VIC , Australia
| | - Christopher C Rowe
- Department of Nuclear Medicine and Centre for PET, Austin Health , Heidelberg, VIC , Australia ; Department of Medicine, The University of Melbourne , Parkville, VIC , Australia
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De Reuck JL. Histopathological stainings and definitions of vascular disruptions in the elderly brain. Exp Gerontol 2012; 47:834-7. [PMID: 22484252 DOI: 10.1016/j.exger.2012.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/15/2012] [Accepted: 03/19/2012] [Indexed: 11/21/2022]
Abstract
Post-mortem neuropathological examination still remains an important tool not only to confirm the clinical diagnosis of the neurodegenerative dementia but also for research purposes. Cerebrovascular lesions are more and more suspected to be involved in the pathogenesis of Alzheimer dementia (AD). In particular the occurrence of small cerebral bleeds becomes a main topic of interest. Post-mortem brain examination, using standard quantification techniques, allows to determine its bleeding load. In AD amyloid angiopathy is not the only cause of small bleeds, while in other neurodegenerative dementias the bleeding load is low and mainly related to associated disturbances of the blood-brain barrier.
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