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Teipel SJ, Grothe MJ, Filippi M, Fellgiebel A, Dyrba M, Frisoni GB, Meindl T, Bokde ALW, Hampel H, Klöppel S, Hauenstein K. Fractional anisotropy changes in Alzheimer's disease depend on the underlying fiber tract architecture: a multiparametric DTI study using joint independent component analysis. J Alzheimers Dis 2015; 41:69-83. [PMID: 24577476 DOI: 10.3233/jad-131829] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Diffusion tensor imaging (DTI) allows the simultaneous measurement of several diffusion indices that provide complementary information on the substrate of white matter alterations in neurodegenerative diseases. These indices include fractional anisotropy (FA) as measure of fiber tract integrity, and the mode of anisotropy (Mode) reflecting differences in the shape of the diffusion tensor. We used a multivariate approach based on joint independent component analysis of FA and Mode in a large sample of 138 subjects with Alzheimer's disease (AD) dementia, 37 subjects with cerebrospinal fluid biomarker positive mild cognitive impairment (MCI-AD), and 153 healthy elderly controls from the European DTI Study on Dementia to comprehensively study alterations of microstructural white matter integrity in AD dementia and predementia AD. We found a parallel decrease of FA and Mode in intracortically projecting fiber tracts, and a parallel increase of FA and Mode in the corticospinal tract in AD patients compared to controls. Subjects with MCI-AD showed a similar, but spatially more restricted pattern of diffusion changes. Our findings suggest an early axonal degeneration in intracortical projecting fiber tracts in dementia and predementia stages of AD. An increase of Mode, parallel to an increase of FA, in the corticospinal tract suggests a more linear shape of diffusion due to loss of crossing fibers along relatively preserved cortico-petal and cortico-fugal fiber tracts in AD. Supporting this interpretation, we found three populations of fiber tracts, namely cortico-petal and cortico-fugal, commissural, and intrahemispherically projecting fiber tracts, in the peak area of parallel FA and Mode increase.
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Affiliation(s)
- Stefan J Teipel
- Department of Psychosomatic Medicine, University of Rostock, Rostock, Germany DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany
| | - Michel J Grothe
- Department of Psychosomatic Medicine, University of Rostock, Rostock, Germany
| | - Massimo Filippi
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, Scientific Institute and University Vita-Salute San Raffaele, Milan, Italy
| | - Andreas Fellgiebel
- Department of Psychiatry, University Medical Center of Mainz, Mainz, Germany
| | - Martin Dyrba
- DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany
| | - Giovanni B Frisoni
- Hopitaux Universitaires de Genève and Université de Genève, IRCCS Centro San Giovanni di Dio, FBF, Brescia, Italy
| | - Thomas Meindl
- Institute for Clinical Radiology, Department of MRI, Ludwig Maximilian University Munich, Munich, Germany
| | - Arun L W Bokde
- Cognitive Systems Group, Discipline of Psychiatry, School of Medicine, Trinity College Dublin, Dublin, Ireland Trinity College Institute of Neuroscience (TCIN), Trinity College Dublin, Dublin, Ireland
| | - Harald Hampel
- Department of Psychiatry, University of Frankfurt, Frankfurt, Germany
| | - Stefan Klöppel
- Department of Psychiatry and Psychotherapy, Freiburg Brain Imaging, University Clinic Freiburg, Freiburg, Germany
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Pelletier A, Periot O, Dilharreguy B, Hiba B, Bordessoules M, Pérès K, Amieva H, Dartigues JF, Allard M, Catheline G. Structural hippocampal network alterations during healthy aging: a multi-modal MRI study. Front Aging Neurosci 2013; 5:84. [PMID: 24367331 PMCID: PMC3852215 DOI: 10.3389/fnagi.2013.00084] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [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: 08/27/2013] [Accepted: 11/16/2013] [Indexed: 11/13/2022] Open
Abstract
While hippocampal atrophy has been described during healthy aging, few studies have examined its relationship with the integrity of White Matter (WM) connecting tracts of the limbic system. This investigation examined WM structural damage specifically related to hippocampal atrophy in healthy aging subjects (n = 129), using morphological MRI to assess hippocampal volume and Diffusion Tensor Imaging (DTI) to assess WM integrity. Subjects with Mild Cognitive Impairment (MCI) or dementia were excluded from the analysis. In our sample, increasing age was significantly associated with reduced hippocampal volume and reduced Fractional Anisotropy (FA) at the level of the fornix and the cingulum bundle. The findings also demonstrate that hippocampal atrophy was specifically associated with reduced FA of the fornix bundle, but it was not related to alteration of the cingulum bundle. Our results indicate that the relationship between hippocampal atrophy and fornix FA values is not due to an independent effect of age on both structures. A recursive regression procedure was applied to evaluate sequential relationships between the alterations of these two brain structures. When both hippocampal atrophy and fornix FA values were included in the same model to predict age, fornix FA values remained significant whereas hippocampal atrophy was no longer significantly associated with age. According to this latter finding, hippocampal atrophy in healthy aging could be mediated by a loss of fornix connections. Structural alterations of this part of the limbic system, which have been associated with neurodegeneration in Alzheimer's disease, result at least in part from the aging process.
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Affiliation(s)
- Amandine Pelletier
- University of Bordeaux, INCIA, UMR 5287 Talence, France ; CNRS, INCIA, UMR 5287 Talence, France ; EPHE Bordeaux, France
| | - Olivier Periot
- University of Bordeaux, INCIA, UMR 5287 Talence, France ; CNRS, INCIA, UMR 5287 Talence, France ; CHU de Bordeaux, Service de Médecine Nucléaire Bordeaux, France
| | - Bixente Dilharreguy
- University of Bordeaux, INCIA, UMR 5287 Talence, France ; CNRS, INCIA, UMR 5287 Talence, France
| | | | - Martine Bordessoules
- University of Bordeaux, INCIA, UMR 5287 Talence, France ; CNRS, INCIA, UMR 5287 Talence, France ; CHU de Bordeaux, Service de Médecine Nucléaire Bordeaux, France
| | - Karine Pérès
- Université de Bordeaux, ISPED, Centre ISPED, INSERM U 897 Bordeaux, France
| | - Hélène Amieva
- Université de Bordeaux, ISPED, Centre ISPED, INSERM U 897 Bordeaux, France
| | | | - Michèle Allard
- University of Bordeaux, INCIA, UMR 5287 Talence, France ; CNRS, INCIA, UMR 5287 Talence, France ; EPHE Bordeaux, France ; CHU de Bordeaux, Service de Médecine Nucléaire Bordeaux, France
| | - Gwénaëlle Catheline
- University of Bordeaux, INCIA, UMR 5287 Talence, France ; CNRS, INCIA, UMR 5287 Talence, France ; EPHE Bordeaux, France
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