Longitudinal white matter changes in frontotemporal dementia subtypes |
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| Authors: | Bonnie Y. K. Lam Glenda M. Halliday Muireann Irish John R. Hodges Olivier Piguet |
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| Affiliation: | 1. Neuroscience Research Australia, Sydney, Australia;2. School of Medical Sciences, University of New South Wales, Sydney, Australia;3. ARC Centre of Excellence in Cognition and its Disorders, University of New South Wales, Sydney, Australia;4. School of Psychology, University of New South Wales, Sydney, Australia |
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| Abstract: | Frontotemporal dementia is a degenerative brain condition characterized by focal atrophy affecting the frontal and temporal lobes predominantly. Changes in white matter with disease progression and their relationship to grey matter atrophy remain unknown in FTD. This study aimed to establish longitudinal white matter changes and compare these changes to regional grey matter atrophy in the main FTD subtypes. Diffusion and T1‐weighted images were collected from behavioral‐variant FTD (bvFTD: 12), progressive non‐fluent aphasia (PNFA: 10), semantic dementia (SD: 11), and 15 controls at baseline and 12 months apart. Changes in white matter integrity were established by fractional anisotropy, mean, axial and radial diffusivity measurements using tract‐based spatial statistics. Patterns of cortical grey matter atrophy were measured using voxel‐based morphometry. At baseline, bvFTD showed severe cross‐sectional changes in orbitofrontal and anterior temporal tracts, which progressed to involve posterior temporal and occipital white matter over the 12‐month. In PNFA, cross‐sectional changes occurred bilaterally in frontotemporal white matter (left > right), with longitudinal changes more prominent on the right. Initial white matter changes in SD were circumscribed to the left temporal lobe, with longitudinal changes extending to bilateral frontotemporal tracts. In contrast, progression of grey matter change over time was less pronounced in all FTD subtypes. Mean diffusivity was most sensitive in detecting baseline changes while fractional anisotropy and radial diffusivity revealed greatest changes over time, possibly reflecting different underlying pathological processes with disease progression. Our results indicate that investigations of white matter changes reveal important differences across FTD syndromes with disease progression. Hum Brain Mapp 35:3547–3557, 2014. © 2013 Wiley Periodicals, Inc . |
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| Keywords: | frontotemporal dementia longitudinal white matter changes diffusion tensor imaging tract‐based spatial statistic voxel‐based morphometry |
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