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Hedden T, Mormino EC, Amariglio RE, Younger AP, Schultz AP, Becker JA, Buckner RL, Johnson KA, Sperling RA, Rentz DM. Cognitive profile of amyloid burden and white matter hyperintensities in cognitively normal older adults. J Neurosci 2012; 32:16233-42. [PMID: 23152607 PMCID: PMC3523110 DOI: 10.1523/jneurosci.2462-12.2012] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 09/10/2012] [Accepted: 09/17/2012] [Indexed: 11/21/2022] Open
Abstract
Amyloid burden and white matter hyperintensities (WMH) are two common markers of neurodegeneration present in advanced aging. Each represents a potential early indicator of an age-related neurological disorder that impacts cognition. The presence of amyloid is observed in a substantial subset of cognitively normal older adults, but the literature remains equivocal regarding whether amyloid in nondemented populations is deleterious to cognition. Similarly, WMH are detected in many nondemented older adults and there is a body of evidence indicating that WMH are associated with decreased executive function and other cognitive domains. The current study investigated amyloid burden and WMH in clinically normal older adult humans aged 65-86 (N = 168) and examined each biomarker's relation with cognitive domains of episodic memory, executive function, and speed of processing. Factors for each domain were derived from a neuropsychological battery on a theoretical basis without reference to the relation between cognition and the biomarkers. Amyloid burden and WMH were not correlated with one another. Age was associated with lower performance in all cognitive domains, while higher estimated verbal intelligence was associated with higher performance in all domains. Hypothesis-driven tests revealed that amyloid burden and WMH had distinct cognitive profiles, with amyloid burden having a specific influence on episodic memory and WMH primarily associated with executive function but having broad (but lesser) effects on the other domains. These findings suggest that even before clinical impairment, amyloid burden and WMH likely represent neuropathological cascades with distinct etiologies and dissociable influences on cognition.
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Affiliation(s)
- Trey Hedden
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
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Behrendt G, Baer K, Buffo A, Curtis MA, Faull RL, Rees MI, Götz M, Dimou L. Dynamic changes in myelin aberrations and oligodendrocyte generation in chronic amyloidosis in mice and men. Glia 2012; 61:273-86. [PMID: 23090919 DOI: 10.1002/glia.22432] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 09/11/2012] [Indexed: 11/08/2022]
Abstract
Myelin loss is frequently observed in human Alzheimer's disease (AD) and may constitute to AD-related cognitive decline. A potential source to repair myelin defects are the oligodendrocyte progenitor cells (OPCs) present in an adult brain. However, until now, little is known about the reaction of these cells toward amyloid plaque deposition neither in human AD patients nor in the appropriate mouse models. Therefore, we analyzed cells of the oligodendrocyte lineage in a mouse model with chronic plaque deposition (APPPS1 mice) and samples from human patients. In APPPS1 mice defects in myelin integrity and myelin amount were prevalent at 6 months of age but normalized to control levels in 9-month-old mice. Concomitantly, we observed an increase in the proliferation and differentiation of OPCs in the APPPS1 mice at this specific time window (6-8 months) implying that improvements in myelin aberrations may result from repair mechanisms mediated by OPCs. However, while we observed a higher number of cells of the oligodendrocyte lineage (Olig2+ cells) in APPPS1 mice, OLIG2+ cells were decreased in number in postmortem human AD cortex. Our data demonstrate that oligodendrocyte progenitors specifically react to amyloid plaque deposition in an AD-related mouse model as well as in human AD pathology, although with distinct outcomes. Strikingly, possible repair mechanisms from newly generated oligodendrocytes are evident in APPPS1 mice, whereas a similar reaction of oligodendrocyte progenitors seems to be strongly limited in final stages of human AD pathology.
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Affiliation(s)
- Gwendolyn Behrendt
- Department of Physiological Genomics, Institute of Physiology, Ludwig-Maximilians University, Munich, Germany
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Yusko EC, Prangkio P, Sept D, Rollings RC, Li J, Mayer M. Single-particle characterization of Aβ oligomers in solution. ACS NANO 2012; 6:5909-5919. [PMID: 22686709 PMCID: PMC3418869 DOI: 10.1021/nn300542q] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Determining the pathological role of amyloids in amyloid-associated diseases will require a method for characterizing the dynamic distributions in size and shape of amyloid oligomers with high resolution. Here, we explored the potential of resistive-pulse sensing through lipid bilayer-coated nanopores to measure the size of individual amyloid-β oligomers directly in solution and without chemical modification. This method classified individual amyloid-β aggregates as spherical oligomers, protofibrils, or mature fibers and made it possible to account for the large heterogeneity of amyloid-β aggregate sizes. The approach revealed the distribution of protofibrillar lengths (12- to 155 -mer) as well as the average cross-sectional area of protofibrils and fibers.
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Affiliation(s)
- Erik C. Yusko
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Panchika Prangkio
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - David Sept
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Center for Computational Medicine and Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Ryan C. Rollings
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, 72701, USA
| | - Jiali Li
- Department of Physics, University of Arkansas, Fayetteville, Arkansas, 72701, USA
| | - Michael Mayer
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
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Hedden T, Van Dijk KRA, Shire EH, Sperling RA, Johnson KA, Buckner RL. Failure to modulate attentional control in advanced aging linked to white matter pathology. Cereb Cortex 2012; 22:1038-51. [PMID: 21765181 PMCID: PMC3328340 DOI: 10.1093/cercor/bhr172] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Advanced aging is associated with reduced attentional control and less flexible information processing. Here, the origins of these cognitive effects were explored using a functional magnetic resonance imaging task that systematically varied demands to shift attention and inhibit irrelevant information across task blocks. Prefrontal and parietal regions previously implicated in attentional control were recruited by the task and most so for the most demanding task configurations. A subset of older individuals did not modulate activity in frontal and parietal regions in response to changing task requirements. Older adults who did not dynamically modulate activity underperformed their peers and scored more poorly on neuropsychological measures of executive function and speed of processing. Examining 2 markers of preclinical pathology in older adults revealed that white matter hyperintensities (WMHs), but not high amyloid burden, were associated with failure to modulate activity in response to changing task demands. In contrast, high amyloid burden was associated with alterations in default network activity. These results suggest failure to modulate frontal and parietal activity reflects a disruptive process in advanced aging associated with specific neuropathologic processes.
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Affiliation(s)
- Trey Hedden
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
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Marchant NL, Reed BR, DeCarli CS, Madison CM, Weiner MW, Chui HC, Jagust WJ. Cerebrovascular disease, β-amyloid, and cognition in aging. Neurobiol Aging 2011; 33:1006.e25-36. [PMID: 22048124 DOI: 10.1016/j.neurobiolaging.2011.10.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/28/2011] [Accepted: 10/03/2011] [Indexed: 12/22/2022]
Abstract
The present study evaluated cerebrovascular disease (CVD), β-amyloid (Aβ), and cognition in clinically normal elderly adults. Fifty-four participants underwent magnetic resonance imaging (MRI), Pittsburgh compound B (PIB)-positron emission tomography (PET) imaging, and neuropsychological evaluation. High white matter hyperintensity burden and/or presence of infarct defined CVD status (CVD-: n = 27; CVD+: n = 27). PIB-positron emission tomography ratios of Aβ deposition were extracted using Logan plotting (cerebellar reference). Presence of high levels of Aβ in prespecified regions determined PIB status (PIB-: n = 33; PIB+: n = 21). Executive functioning and episodic memory were measured using composite scales. CVD and Aβ, defined as dichotomous or continuous variables, were unrelated to one another. CVD+ participants showed lower executive functioning (p = 0.001) when compared with CVD- individuals. Neither PIB status nor amount of Aβ affected cognition (ps ≥ 0.45), and there was no statistical interaction between CVD and PIB on either cognitive measure. Within this spectrum of normal aging CVD and Aβ aggregation appear to be independent processes with CVD primarily affecting cognition.
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Affiliation(s)
- Natalie L Marchant
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA.
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Gary DS, Malone M, Capestany P, Houdayer T, McDonald JW. Electrical stimulation promotes the survival of oligodendrocytes in mixed cortical cultures. J Neurosci Res 2011; 90:72-83. [PMID: 21932370 DOI: 10.1002/jnr.22717] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/09/2011] [Accepted: 05/19/2011] [Indexed: 11/07/2022]
Abstract
Oligodendrocyte (OLG) death plays a major role in white matter dysfunction and demyelination following injury to the CNS. Axonal contact, communication, and neuronal activity appear to promote OLG survival and function in cell culture and during development. The application of electrical stimulation to mixed neural cultures has been shown to promote OLG differentiation and the formation of myelin in vitro. Here we show that OLG viability can be significantly enhanced in mixed cortical cultures by applying biphasic pulses of electrical stimulation (ESTIM). Enhanced survival via ESTIM requires the presence of neurons and is suppressed by inhibition of voltage-gated sodium channels. Additionally, contact between the axon and OLG is necessary for ESTIM to promote OLG survival. This report suggests that patterned neuronal activity could repress delayed progression of white matter injury and promote CNS repair in neurological conditions that involve white matter damage.
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Affiliation(s)
- Devin S Gary
- The International Center for Spinal Cord Injury, Hugo W. Moser Research Institute at Kennedy Krieger, Baltimore, Maryland 21205, USA.
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Weidner AM, Housley M, Murphy MP, Levine H. Purified high molecular weight synthetic Aβ(1-42) and biological Aβ oligomers are equipotent in rapidly inducing MTT formazan exocytosis. Neurosci Lett 2011; 497:1-5. [PMID: 21504780 DOI: 10.1016/j.neulet.2011.03.082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/21/2011] [Accepted: 03/28/2011] [Indexed: 11/28/2022]
Abstract
Synthetic soluble Aβ oligomers are often used as a surrogate for biologic material in a number of model systems. We compared the activity of Aβ oligomers (synthetic and cell culture media derived) on the human SH-SY5Y neuroblastoma and C2C12 mouse myoblast cell lines in a novel, modified MTT assay. Separating oligomers from monomeric peptide by size exclusion chromatography produced effects at peptide concentrations approaching physiologic levels (10-100 nM). Purified oligomers, but not monomers or fibrils, elicited an increase of a detergent-insoluble form of MTT formazan within 2h as opposed to a control toxin (H(2)O(2)). This effect was comparable for biological and synthetic peptide in both cell types. Monomeric Aβ attenuated the effect of soluble oligomers. This study suggests that the activities of biological and synthetic oligomers are indistinguishable during early stages of Aβ oligomer-cell interaction.
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Affiliation(s)
- Adam M Weidner
- Department of Cellular and Molecular Biochemistry, Center on Aging, Center for Structural Biology, University of Kentucky, 800 S. Limestone Street, Lexington, KY 40536-0230, United States.
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Carmichael O, Lockhart S. The role of diffusion tensor imaging in the study of cognitive aging. Curr Top Behav Neurosci 2011; 11:289-320. [PMID: 22081443 DOI: 10.1007/7854_2011_176] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This chapter gives an overview of the role that diffusion tensor MRI (DTI) can play in the study of cognitive decline that is associated with advancing age. A brief overview of biological injury processes that impinge on the aging brain is provided, and their overall effect on the integrity of neural architecture is described. Cognitive decline associated with aging, and white matter connectivity degradation as a biological substrate for that decline, is then described. We then briefly describe the technology of DTI as a means for in vivo, non-invasive interrogation of white matter connectivity, and relate it to FLAIR, a more traditional MRI method for assessing white matter injury. We then survey the existing findings on relationships between aging-associated neuropathological processes and DTI measurements on one hand; and relationships between DTI measurements and late-life cognitive function on the other. We conclude with a summary of current research directions in relation to DTI studies of cognitive aging.
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Affiliation(s)
- Owen Carmichael
- Neurology Department, University of California, Davis, Davis, CA, USA,
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