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Lewis JD, O’Reilly C, Bock E, Theilmann RJ, Townsend J. Aging-Related Differences in Structural and Functional Interhemispheric Connectivity. Cereb Cortex 2022; 32:1379-1389. [PMID: 34496021 PMCID: PMC9190305 DOI: 10.1093/cercor/bhab275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/18/2021] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
There is substantial evidence of age-related declines in anatomical connectivity during adulthood, with associated alterations in functional connectivity. But the relation of those functional alterations to the structural reductions is unclear. The complexities of both the structural and the functional connectomes make it difficult to determine such relationships. We pursue this question with methods, based on animal research, that specifically target the interhemispheric connections between the visual cortices. We collect t1- and diffusion-weighted imaging data from which we assess the integrity of the white matter interconnecting the bilateral visual cortices. Functional connectivity between the visual cortices is measured with electroencephalography during the presentation of drifting sinusoidal gratings that agree or conflict across hemifields. Our results show age-related reductions in the integrity of the white matter interconnecting the visual cortices, and age-related increases in the difference in functional interhemispheric lagged coherence between agreeing versus disagreeing visual stimuli. We show that integrity of the white matter in the splenium of the corpus callosum predicts the differences in lagged coherence for the agreeing versus disagreeing stimuli; and that this relationship is mediated by age. These results give new insight into the causal relationship between age and functional connectivity.
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Affiliation(s)
- John D Lewis
- McGill Centre for Integrative Neuroscience, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Christian O’Reilly
- Azrieli Centre for Autism Research, McGill University, Montreal, Quebec, H3A 2B4, Canada
| | - Elizabeth Bock
- McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC, H3A 2B4, Canada
| | | | - Jeanne Townsend
- Department of Neurosciences, UC San Diego, La Jolla, CA 92093, USA
- Research on Aging and Development Laboratory, UC San Diego, La Jolla, CA 92037, USA
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Serbruyns L, Leunissen I, van Ruitenbeek P, Pauwels L, Caeyenberghs K, Solesio-Jofre E, Geurts M, Cuypers K, Meesen RL, Sunaert S, Leemans A, Swinnen SP. Alterations in brain white matter contributing to age-related slowing of task switching performance: The role of radial diffusivity and magnetization transfer ratio. Hum Brain Mapp 2016; 37:4084-4098. [PMID: 27571231 PMCID: PMC6867406 DOI: 10.1002/hbm.23297] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 05/30/2016] [Accepted: 06/19/2016] [Indexed: 12/26/2022] Open
Abstract
Successfully switching between tasks is critical in many daily activities. Age-related slowing of this switching behavior has been documented extensively, but the underlying neural mechanisms remain unclear. Here, we investigated the contribution of brain white matter changes associated with myelin alterations to age-related slowing of switching performance. Diffusion tensor imaging derived radial diffusivity (RD) and magnetization transfer imaging derived magnetization transfer ratio (MTR) were selected as myelin sensitive measures. These metrics were studied in relation to mixing cost (i.e., the increase in reaction time during task blocks that require task switching) on a local-global switching task in young (n = 24) and older (n = 22) adults. Results showed that higher age was associated with widespread increases in RD and decreases in MTR, indicative of white matter deterioration, possibly due to demyelination. Older adults also showed a higher mixing cost, implying slowing of switching performance. Finally, mediation analyses demonstrated that decreases in MTR of the bilateral superior corona radiata contributed to the observed slowing of switching performance with increasing age. These findings provide evidence for a role of cortico-subcortical white matter changes in task switching performance deterioration with healthy aging. Hum Brain Mapp 37:4084-4098, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Leen Serbruyns
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Inge Leunissen
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Peter van Ruitenbeek
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Lisa Pauwels
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Karen Caeyenberghs
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
- School of Psychology, Faculty of Health Sciences, Australian Catholic University, Australia
| | - Elena Solesio-Jofre
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Monique Geurts
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Koen Cuypers
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
- REVAL Rehabilitation Research Centre, Biomedical Research Institute, Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium
| | - Raf L Meesen
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
- REVAL Rehabilitation Research Centre, Biomedical Research Institute, Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium
| | - Stefan Sunaert
- Medical Imaging Research Center, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Alexander Leemans
- Image Sciences Institute, University Medical Center Utrecht, The Netherlands
| | - Stephan P Swinnen
- Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
- KU Leuven, Leuven Research Institute for Neuroscience & Disease (LIND), Belgium.
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Bal S, Goyal M, Smith E, Demchuk AM. Central nervous system imaging in diabetic cerebrovascular diseases and white matter hyperintensities. HANDBOOK OF CLINICAL NEUROLOGY 2014; 126:291-315. [PMID: 25410230 DOI: 10.1016/b978-0-444-53480-4.00021-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Diabetes mellitus is an important vascular risk factor for cerebrovascular disease. This occurs through pathophysiologic changes to the microcirculation as arteriolosclerosis and to the macrocirculation as large artery atherosclerosis. Imaging techniques can provide detailed visualization of the cerebrovasculature using CT (computed tomography) angiography and MR (magnetic resonance) angiography. Newer techniques focused on advanced parenchymal imaging include CT perfusion, quantitative MRI, and diffusion tensor imaging; each identifies brain lesion burden due to diabetes mellitus. These imaging approaches have provided insights into the diabetes mellitus brain and cerebral circulation pathophysiology. Imaging has taught us that diabetics develop cerebral atrophy, silent infarcts, and white matter disease more rapidly than other patient populations. Longitudinal studies are needed to quantify the rate and extent of such structural brain and blood vessel changes and how they relate to cognitive decline. Diabetes prevention and treatment strategies will then be possible to slow the development of such changes.
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Affiliation(s)
- Simerpreet Bal
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada
| | - Mayank Goyal
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada
| | - Eric Smith
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada
| | - Andrew M Demchuk
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada.
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Mascalchi M, Toschi N, Ginestroni A, Giannelli M, Nicolai E, Aiello M, Soricelli A, Diciotti S. Gender, age-related, and regional differences of the magnetization transfer ratio of the cortical and subcortical brain gray matter. J Magn Reson Imaging 2013; 40:360-6. [PMID: 24923993 DOI: 10.1002/jmri.24355] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/29/2013] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To explore gender, age-related, and regional differences of magnetization transfer ratio (MTR) of brain cortical and subcortical gray matter (GM). MATERIALS AND METHODS In all, 102 healthy subjects (51 women and 51 men; range 25-84 years) were examined with 3-mm thick MT images. We assessed MTR in automatically segmented GM structures including frontal, parietal-insular, temporal, and occipital cortex, caudate, pallidus and putamen, and cerebellar cortex. A general linear model analysis was conducted to ascertain the linear and quadratic relationship among the MTR and gender, age, and anatomical structure. RESULTS The effect of gender was borderline (P = 0.07) in all GM structures (with higher MTR values in men), whereas age showed a significant linear as well as quadratic effect in all cortical and subcortical GM structures (P ≤ 0.001). Quadratic age-related decrease in MTR began at about 40 years of age. Mean and standard deviation (SD) of MTR had the following decreasing order: thalamus (58.3 + 0.8), pallidus (56.8 ± 1.3), caudate (55.5 ± 1.6) and putamen (54.6 ± 1.1); temporal (56.8 ± 0.9), parietal-insular (56.8 ± 1.1), frontal (56.5 ± 1.1), occipital (55.4 ± 1.0) and cerebellar (53.2 ± 1.0) cortex. In post-hoc testing, all regional pairwise differences were statistically significant except pallidus vs. temporal or parietal-insular cortex, caudate vs. occipital cortex, frontal vs. parietal-insular or temporal cortex. CONCLUSION MTR of the cortical and subcortical brain GM structures decreases quadratically after midlife and shows significant regional differences.
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Affiliation(s)
- Mario Mascalchi
- Quantitative and Functional Neuroradiology Program at Meyer Children's Hospital and Careggi Hospital of Florence, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
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Abstract
To understand how normal variations in white matter relate to cognition, magnetization transfer imaging ratios (MTR) of a hypothesized neural network were associated with a test of visual selective attention (VST). Healthy adults (N = 16) without abnormal signal on brain scans viewed a version of DeSchepper and Treisman's test of VST (1996) with two levels of processing (novel shape matching with and without distractors, contingency feedback). A hypothesized neural network and component regions was significantly associated with accuracy and response times when distractors were present, with betas predicting 55% of variance in accuracy, and 59% of response times. MTR for anterior and posterior cingulate, prefrontal region, and thalami comprised a model predicting 55% of accuracy when distractors were present, and the anterior cingulate accounted for the majority of this effect. Prefrontal MTR predicted longer response times which was associated with increased accuracy. Distal neural areas involved in complex, processing-driven tasks (error processing, response selection, and variable response competition and processing load) may be dependent on white matter fibers to connect distal brain regions/nuclei of a macronetwork, including prefrontal executive functions.
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Levesque IR, Sled JG, Narayanan S, Giacomini PS, Ribeiro LT, Arnold DL, Pike GB. Reproducibility of quantitative magnetization-transfer imaging parameters from repeated measurements. Magn Reson Med 2011; 64:391-400. [PMID: 20665783 DOI: 10.1002/mrm.22350] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Quantitative magnetization-transfer imaging methods provide in vivo estimates of parameters of the two-pool model for magnetization-transfer in tissue. The goal of this study was to evaluate the reproducibility of quantitative magnetization-transfer imaging parameter estimates in healthy subjects. Magnetization-transfer-weighted and T(1) relaxometry data were acquired in five healthy subjects at multiple time points, and the variability of the resulting fitted magnetization-transfer parameters was evaluated. The impact of subsampling the magnetization-transfer data and correcting field inhomogeneities was also evaluated. The key parameters measured in this study had an average variability, across time points, of 4.7% for the relative size of the restricted pool (F), 7.3% for the forward exchange constant (k(f)), 1.9% for the free pool spin-lattice relaxation constant (R(1f)), 4.5% for the T(2) of the free pool (T(2f)), and 2.3% for the T(2) of the restricted pool (T(2r)). Our findings show that serial quantitative magnetization-transfer imaging experiments can be performed reliably, with good reproducibility of the model parameter estimates, and demonstrate the reproducibility of acquisition schemes with fewer magnetization-transfer contrasts. This establishes the feasibility of this technique for monitoring patients affected by degenerative white matter diseases while providing critical data to estimate the statistical power of such studies.
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Affiliation(s)
- Ives R Levesque
- McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
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Rosano C, Sigurdsson S, Siggeirsdottir K, Phillips CL, Garcia M, Jonsson PV, Eiriksdottir G, Newman AB, Harris TB, van Buchem MA, Gudnason V, Launer LJ. Magnetization transfer imaging, white matter hyperintensities, brain atrophy and slower gait in older men and women. Neurobiol Aging 2010; 31:1197-204. [PMID: 18774624 PMCID: PMC2873052 DOI: 10.1016/j.neurobiolaging.2008.08.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 07/30/2008] [Accepted: 08/04/2008] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To assess whether markers of micro- and macrostructural brain abnormalities are associated with slower gait in older men and women independent of each other, and also independent of health-related conditions and of behavioral, cognitive and peripheral function. METHODS Magnetization transfer ratio [MTR], white matter hyperintensities [WMH], brain atrophy [BA] and brain infarcts [BI] were measured in 795 participants of the AGES-Reykjavik Study cohort (mean 75.6 years, 58.9% women). RESULTS In women, lower MTR, higher WMH and BA, but not BI, remained associated with slower gait independent of each other and of other covariates. In men, WMH and BA, but not MTR or BI, remained associated with slower gait independently of each other. Only muscle strength, executive control function and depression test scores substantially attenuated these associations. INTERPRETATIONS MTR in older adults may be an important additional marker of brain abnormalities associated with slower gait. Studies to explore the relationship between brain micro- and macrostructural abnormalities with gait and the role of mediating factors are warranted.
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Affiliation(s)
- Caterina Rosano
- University of Pittsburgh, Graduate School of Public Health, Pittsburgh, PA, USA.
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Schuff N, Suhy J, Goldman R, Xu Y, Sun Y, Truran-Sacrey D, Murthy A. An MRI substudy of a donepezil clinical trial in mild cognitive impairment. Neurobiol Aging 2010; 32:2318.e31-41. [PMID: 20541841 DOI: 10.1016/j.neurobiolaging.2010.04.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 03/24/2010] [Accepted: 04/05/2010] [Indexed: 11/24/2022]
Abstract
A magnetic resonance imaging (MRI) study was conducted as part of an intervention study in subjects with amnestic mild cognitive impairment (aMCI) to assess donepezil's treatment effect on brain atrophy. Adults with aMCI were randomly assigned to double-blind treatment with 10 mg/day donepezil hydrochloride or placebo for 48 weeks. Brain MRI scans were acquired at baseline and endpoint. The primary outcome measure was annualized percentage change (APC) in hippocampal volume; the main secondary outcome measure was APC in whole brain volumes. An analysis of variance (ANOVA) model including terms for treatment, site, and age was used to compare the treatment groups. APCs for hippocampal volumes were not significantly different between treatment groups. There were significant differences favoring the donepezil group for total (p = 0.001), ventricular region (p = 0.0002), and cortical region (p = 0.003) whole brain volumes. Although the primary MRI outcome measure was negative, the main secondary MRI outcome measure showed a positive result. These findings suggest a treatment effect of donepezil on brain atrophy in aMCI.
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Affiliation(s)
- Norbert Schuff
- Center for Imaging of Neurodegenerative Disease, Veterans Affairs Medical Center, 114M, 4150 Clement St., San Francisco, CA 94121, USA.
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9
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Early structural changes in individuals at risk of familial Alzheimer's disease: a volumetry and magnetization transfer MR imaging study. J Neurol 2009; 256:925-32. [PMID: 19252791 DOI: 10.1007/s00415-009-5044-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 01/19/2009] [Accepted: 01/20/2009] [Indexed: 10/21/2022]
Abstract
Presenilin 1 (PS1) mutation carriers provide the opportunity to asses early features of neurodegeneration in familial Alzheimer's disease (AD). Gray matter (GM) regional volume loss and decrease of magnetization transfer ratio (MTR) consistent with microstructural changes have been reported in sporadic AD. We performed a regional volumetric and MTR analysis in carriers of PS1 mutations. Six non-demented mutated PS1 carriers (5 with memory deficits) and 14 healthy subjects were examined with high resolution T1-weighted images for volumetry and with T2* weighted images for MTR. Cortical GM volume and MTR values were derived. Compared to healthy controls, the GM volume of the left temporal and inferior parietal cortex and the MTR of the temporal cortex bilaterally were significantly decreased in PS1 gene carriers. In the latter, the temporal lobe MTR showed a trend for correlation with memory and executive function scores. Early neurodegeneration in non-demented subjects at risk for familial AD may be associated with atrophy and decreased MTR in the temporal cortex.
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Gunning-Dixon FM, Brickman AM, Cheng JC, Alexopoulos GS. Aging of cerebral white matter: a review of MRI findings. Int J Geriatr Psychiatry 2009; 24:109-17. [PMID: 18637641 PMCID: PMC2631089 DOI: 10.1002/gps.2087] [Citation(s) in RCA: 353] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Cerebral aging is a complex and heterogeneous process that is associated with a high degree of inter-individual variability. Structural magnetic resonance imaging (MRI) can be used to identify and quantify non-disease-related aging of the cerebral white matter. METHODS The present article reviews the findings from several MRI techniques, including morphometric approaches, study of white matter hyperintensities, diffusion tensor imaging, and magnetization transfer imaging, that have been used to examine aging of the cerebral white matter. Furthermore, the relationship of MRI indices of white matter integrity to age-related cognitive declines is reported. RESULTS A general pattern of age-related preservation and decline emerges indicating that the prefrontal white matter is most susceptible to the influence of age. Studies that combine MRI with cognitive measures suggest that such age-related reductions in white matter integrity may produce a disconnection state that underlies some of the age-related performance declines in age-sensitive cognitive domains. CONCLUSIONS White matter aging may contribute to a disconnection state that is associated with declines in episodic memory, executive functions, and information processing speed.
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Affiliation(s)
- Faith M. Gunning-Dixon
- Institute of Geriatric Psychiatry, Department of Psychiatry, Weill Cornell Medical College
| | - Adam M. Brickman
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain College of Physicians and Surgeons, Columbia University
| | - Janice C. Cheng
- Institute of Geriatric Psychiatry, Department of Psychiatry, Weill Cornell Medical College
| | - George S. Alexopoulos
- Institute of Geriatric Psychiatry, Department of Psychiatry, Weill Cornell Medical College
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Agosta F, Laganà M, Valsasina P, Sala S, Dall'Occhio L, Sormani MP, Judica E, Filippi M. Evidence for cervical cord tissue disorganisation with aging by diffusion tensor MRI. Neuroimage 2007; 36:728-35. [PMID: 17490894 DOI: 10.1016/j.neuroimage.2007.03.048] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 03/27/2007] [Accepted: 03/27/2007] [Indexed: 10/23/2022] Open
Abstract
This study investigated the influence of normal aging on cervical cord volumetry and diffusivity changes and assessed whether magnetic resonance imaging (MRI) abnormalities of the aging cervical cord and brain are associated. Conventional and diffusion tensor (DT) MRI of the brain and cervical cord were acquired from 96 healthy subjects (age range=13-70 years). Cross-sectional area, mean diffusivity (MD) and fractional anisotropy (FA) of the cervical cord were measured. Volumetry and diffusivity metrics were also obtained for the brain white matter (WM) and grey matter (GM) (overall and cortical). No cervical cord lesions were seen on conventional MR images from all subjects. Degenerative vertebral column changes (not associated to cord compression) were found in 41 subjects (43%). Average FA of the cervical cord, but not average MD and cross-sectional area, was correlated with age (r=-0.70, p<0.001). Additionally, T2 brain lesion volume, normalised brain volume (NBV), normalised global and cortical brain GM volumes and average MD of the brain GM and WM also correlated with age (r values ranging from -0.83 to 0.62). Only brain WM average FA was weakly correlated with cervical cord average FA (r=0.25, p=0.02). The final multivariate model retained cord average FA (r=-0.37, p<0.001), normalised cortical GM volume (r=-0.56, p<0.001) and NBV (r=-0.22, p=0.04) as independent correlates of age (r2=0.76). Cervical cord is vulnerable to aging. The decrease of FA, in the absence of atrophy and MD changes, suggests gliosis as the most likely pathological feature of the aging cord.
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Affiliation(s)
- Federica Agosta
- Neuroimaging Research Unit, Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Milan, Italy
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Wozniak JR, Lim KO. Advances in white matter imaging: a review of in vivo magnetic resonance methodologies and their applicability to the study of development and aging. Neurosci Biobehav Rev 2006; 30:762-74. [PMID: 16890990 PMCID: PMC2895765 DOI: 10.1016/j.neubiorev.2006.06.003] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Several newer magnetic resonance imaging (MRI) techniques are increasingly being applied to the study of white matter development and pathology across the lifespan. These techniques go beyond traditional macrostructural volumetric methods and provide valuable information about underlying tissue integrity and organization at the microstructural and biochemical levels. We first provide an overview of white matter development and discuss the role of white matter and myelin in cognitive function. We also review available studies of development that have employed traditional volumetric measures. Then, we discuss the contributions of four newer imaging paradigms to our understanding of brain development and aging. These paradigms are Diffusion Tensor Imaging (DTI), Magnetization Transfer Imaging (MTI), T2-Relaxography, and Magnetic Resonance Spectroscopy (MRS). Studies examining brain development during childhood and adulthood as well as studies of the effects of aging are discussed.
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Affiliation(s)
- Jeffrey R. Wozniak
- Department of Psychiatry, University of Minnesota, F256/2B West, 2450 Riverside Ave., Minneapolis, MN 55454, USA
- Corresponding author. Tel.: +612 273 9741
| | - Kelvin O. Lim
- Drs. T.J. and Ella M. Arneson Endowed Chair, University of Minnesota, F282/2A West, 2450 Riverside Ave., Minneapolis, MN 55454, USA
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Filley CM, Halliday W, Kleinschmidt-DeMasters BK. The effects of toluene on the central nervous system. J Neuropathol Exp Neurol 2004; 63:1-12. [PMID: 14748556 DOI: 10.1093/jnen/63.1.1] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In recent decades the organic solvent toluene (methylbenzene) has emerged as one of the best-studied neurotoxins. Long-term and intense exposure to toluene vapors in humans who abuse spray paint and related substances has led to the recognition that toluene has a severe impact on central nervous system myelin. Chronic toluene abuse produces a devastating neurological disorder, of which dementia is the most disabling component. The clinical syndrome, toluene leukoencephalopathy, can be detected by a combination of characteristic symptoms and signs, detailed neurobehavioral evaluation, and brain magnetic resonance imaging. In this paper, we consider the impact of toluene abuse on our society, describe the specific neurobehavioral deficits in toluene leukoencephalopathy, review the spectrum of neuroimaging findings in patients with this disorder, summarize the teratogenic effects of toluene in both humans and animal models, and offer possible explanations for the range of neuropathological damage seen in brains of individuals who chronically abuse toluene.
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Affiliation(s)
- Christopher M Filley
- Department of Neurology, University of Colorado School of Medicine, Denver, Colorado 80262, USA
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Hanyu H, Asano T, Sakurai H, Iwamoto T, Takasaki M, Shindo H, Abe K. Magnetization transfer ratio in cerebral white matter lesions of Binswanger's disease. J Neurol Sci 1999; 166:85-90. [PMID: 10475100 DOI: 10.1016/s0022-510x(99)00122-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We measured the magnetization transfer (MT) ratios in white matter lesions of Binswanger's disease (BD) and compared them with BD and with similar-appearing changes in non-demented elderly subjects and cerebral infarction. Four subject groups were studied: 30 patients with BD and periventricular hyperintensity (PVH) on MRI, 29 patients with ischemic cerebrovascular event with PVH but no dementia, 17 patients with old cerebral infarction, and 26 elderly control subjects. MT ratios were calculated for areas of PVH in BD and non-demented subjects, of infarction, and of normal-appearing white matter in controls. The decrease in MT ratios for areas in PVH of non-demented subjects and BD and in infarction compared with normal white matter in controls was 12, 20, and 35%, respectively. The MT ratio in PVH of BD was significantly lower than that in PVH of non-demented subjects, but not to the levels seen in areas of infarction. There was a significant high correlation between the Mini-Mental State Examination score and MT ratio for area of PVH (r = 0.790). MT ratio distinguishes PVH in BD patients from those in non-demented subjects, suggesting underlying histopathological differences. Tissue damage in white matter lesions of BD may be more severe than that in non-demented subjects, but not as much as with complete infarction.
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Affiliation(s)
- H Hanyu
- Department of Geriatric Medicine, Tokyo Medical University, Japan
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Schuff N, Amend DL, Meyerhoff DJ, Tanabe JL, Norman D, Fein G, Weiner MW. Alzheimer disease: quantitative H-1 MR spectroscopic imaging of frontoparietal brain. Radiology 1998; 207:91-102. [PMID: 9530304 PMCID: PMC2753252 DOI: 10.1148/radiology.207.1.9530304] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE To replicate previous hydrogen-1 magnetic resonance (MR) spectroscopic imaging findings of metabolic abnormalities in patients with Alzheimer disease (AD), to verify that metabolic abnormalities are not an artifact of structural variations measured at MR imaging, to determine whether metabolic changes correlate with dementia severity, and to test whether MR imaging and MR spectroscopic imaging findings together improve ability to differentiate AD. MATERIALS AND METHODS MR spectroscopic imaging and MR imaging were performed in 28 patients with AD and 22 healthy elderly subjects. Spectroscopic imaging data were coregistered with MR imaging segmentation data to obtain volume-corrected metabolite concentrations. RESULTS Consistent with previous results, N-acetyl aspartate (NAA) levels were statistically significantly reduced in frontal and posterior mesial cortex of AD patients, presumably due to neuronal loss. NAA level reductions were independent of structural variations measured at MR imaging and, in parietal mesial cortex, were correlated mildly with dementia severity. Spectroscopic imaging findings of NAA level combined with MR imaging measures did not improve discrimination power for AD relative to that of MR imaging alone. CONCLUSION Reduced NAA levels in frontoparietal brain are of limited use for diagnosis of AD. However, they are not an artifact of structural variations and thus may provide useful information for the understanding of the pathologic processes underlying AD.
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Key Words
- brain, diseases, 13.83
- brain, metabolism
- brain, mr, 13.121411, 13.12145, 13.12146
- dementia, 13.83
- magnetic resonance (mr), spectroscopy, 13.1215
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Affiliation(s)
- N Schuff
- Magnetic Resonance Unit, Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA
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