Loss and dispersion of superficial white matter in Alzheimer's disease: a diffusion MRI study.

Autor:	Veale T; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.; UK Dementia Research Institute at UCL, University College London, London, UK., Malone IB; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK., Poole T; Department of Medical Statistics, London School of Hygiene & Tropical Medicine, London, UK., Parker TD; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.; Department of Brain Sciences, Imperial College London, London, UK., Slattery CF; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK., Paterson RW; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.; UK Dementia Research Institute at UCL, University College London, London, UK., Foulkes AJM; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK., Thomas DL; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.; Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, London, UK.; Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, London, UK., Schott JM; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK., Zhang H; Department of Computer Science and Centre for Medical Image Computing, UCL, London, UK., Fox NC; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.; UK Dementia Research Institute at UCL, University College London, London, UK., Cash DM; The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.; UK Dementia Research Institute at UCL, University College London, London, UK.
Jazyk:	angličtina
Zdroj:	Brain communications [Brain Commun] 2021 Nov 15; Vol. 3 (4), pp. fcab272. Date of Electronic Publication: 2021 Nov 15 (Print Publication: 2021).
DOI:	10.1093/braincomms/fcab272
Abstrakt:	Pathological cerebral white matter changes in Alzheimer's disease have been shown using diffusion tensor imaging. Superficial white matter changes are relatively understudied despite their importance in cortico-cortical connections. Measuring superficial white matter degeneration using diffusion tensor imaging is challenging due to its complex organizational structure and proximity to the cortex. To overcome this, we investigated diffusion MRI changes in young-onset Alzheimer's disease using standard diffusion tensor imaging and Neurite Orientation Dispersion and Density Imaging to distinguish between disease-related changes that are degenerative (e.g. loss of myelinated fibres) and organizational (e.g. increased fibre dispersion). Twenty-nine young-onset Alzheimer's disease patients and 22 healthy controls had both single-shell and multi-shell diffusion MRI. We calculated fractional anisotropy, mean diffusivity, neurite density index, orientation dispersion index and tissue fraction (1-free water fraction). Diffusion metrics were sampled in 15 a priori regions of interest at four points along the cortical profile: cortical grey matter, grey/white boundary, superficial white matter (1 mm below grey/white boundary) and superficial/deeper white matter (2 mm below grey/white boundary). To estimate cross-sectional group differences, we used average marginal effects from linear mixed effect models of participants' diffusion metrics along the cortical profile. The superficial white matter of young-onset Alzheimer's disease individuals had lower neurite density index compared to controls in five regions (superior and inferior parietal, precuneus, entorhinal and parahippocampus) (all P  <   0.05), and higher orientation dispersion index in three regions (fusiform, entorhinal and parahippocampus) (all P  <   0.05). Young-onset Alzheimer's disease individuals had lower fractional anisotropy in the entorhinal and parahippocampus regions (both P  <   0.05) and higher fractional anisotropy within the postcentral region ( P  <   0.05). Mean diffusivity was higher in the young-onset Alzheimer's disease group in the parahippocampal region ( P  <   0.05) and lower in the postcentral, precentral and superior temporal regions (all P  <   0.05). In the overlying grey matter, disease-related changes were largely consistent with superficial white matter findings when using neurite density index and fractional anisotropy, but appeared at odds with orientation dispersion and mean diffusivity. Tissue fraction was significantly lower across all grey matter regions in young-onset Alzheimer's disease individuals (all P  <   0.001) but group differences reduced in magnitude and coverage when moving towards the superficial white matter. These results show that microstructural changes occur within superficial white matter and along the cortical profile in individuals with young-onset Alzheimer's disease. Lower neurite density and higher orientation dispersion suggests underlying fibres undergo neurodegeneration and organizational changes, two effects previously indiscernible using standard diffusion tensor metrics in superficial white matter. (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)
Databáze:	MEDLINE
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