This thesis characterises the cortical pattern of degeneration in progressive supranuclear palsy (PSP) and its consequences. Global atrophy was first examined using a recently developed staging scheme in pathologically-proven PSP cases compared with other tauopathies: gross atrophy was not observed in PSP. Quantification of regional volume loss throughout the brain was then used to determine the magnitude of more focal tissue atrophy in PSP, cortical dysfunction was investigated by measuring cerebral blood flow (CBF) changes, and several cortical cellular pathologies were analysed. Any changes observed were related to each other and clinical assessments of motor, cognitive and behavioural abnormalities. At mid-stage PSP, frontal and subcortical atrophy related to decreased CBF in the frontal cortex and cognitive decline. Parietocerebellar CBF increases were also identified (related to frontal CBF deficits) and related to motor and non-motor deficits. By end-stage PSP, focal atrophy had advanced from frontal and subcortical structures to include atrophy in the parietal lobe. Parietal lobe atrophy related to behavioural abnormalities. Histopathological analysis at end-stage revealed that the cortical atrophy and cell loss does not relate to tau deposition. The focal cortical cell loss related exclusively to motor deficits whilst the more widespread cortical tau deposition related to cognitive and behavioural impairments. Both the tau deposition and these non-motor impairments increased in severity over time. The results show that frontal atrophy and dysfunction occurs rapidly and early in PSP and relate to increasing cognitive deficits. Such deficits appear to cause compensatory CBF enhancement in parietocerebellar regions which then also undergo rapid and severe neurodegeneration. These later changes occur in concert with the more classic PSP symptoms, such as oculomotor features. Throughout the disease, the progressive increase in frontotemporal tau deposition contributes to cognitive and behavioural deficits which become most marked late in the disease. The findings strongly suggest that progressive clinical dysfunction in PSP is directly related to progressive cortical degeneration. Cortical degeneration appears to occur in two independent functional networks. Increased CBF in PSP may be a useful early indicator for future neurodegeneration, although the cellular mechanism leading to cell death requires further investigation.
| Identifer | oai:union.ndltd.org:ADTP/215452 |
| Date | January 2006 |
| Creators | Schofield, Emma, Medical Sciences, Faculty of Medicine, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Medical Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Emma Schofield, http://unsworks.unsw.edu.au/copyright |
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