Lewy- and Alzheimer-type pathologies in Parkinson's disease dementia: which is more important?
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ABSTRACT: The relative importance of Lewy- and Alzheimer-type pathologies to dementia in Parkinson's disease remains unclear. We have examined the combined associations of ?-synuclein, tau and amyloid-? accumulation in 56 pathologically confirmed Parkinson's disease cases, 29 of whom had developed dementia. Cortical and subcortical amyloid-? scores were obtained, while tau and ?-synuclein pathologies were rated according to the respective Braak stages. Additionally, cortical Lewy body and Lewy neurite scores were determined and Lewy body densities were generated using morphometry. Non-parametric statistics, together with regression models, receiver-operating characteristic curves and survival analyses were applied. Cortical and striatal amyloid-? scores, Braak tau stages, cortical Lewy body, Lewy neurite scores and Lewy body densities, but not Braak ?-synuclein stages, were all significantly greater in the Parkinson's disease-dementia group (P<0.05), with all the pathologies showing a significant positive correlation to each other (P<0.05). A combination of pathologies [area under the receiver-operating characteristic curve=0.95 (0.88-1.00); P<0.0001] was a better predictor of dementia than the severity of any single pathology. Additionally, cortical amyloid-? scores (r=-0.62; P=0.043) and Braak tau stages (r=-0.52; P=0.028), but not Lewy body scores (r=-0.25; P=0.41) or Braak ?-synuclein stages (r=-0.44; P=0.13), significantly correlated with mini-mental state examination scores in the subset of cases with this information available within the last year of life (n=15). High cortical amyloid-? score (P=0.017) along with an older age at onset (P=0.001) were associated with a shorter time-to-dementia period. A combination of Lewy- and Alzheimer-type pathologies is a robust pathological correlate of dementia in Parkinson's disease, with quantitative and semi-quantitative assessment of Lewy pathology being more informative than Braak ?-synuclein stages. Cortical amyloid-? and age at disease onset seem to determine the rate to dementia.
SUBMITTER: Compta Y
PROVIDER: S-EPMC4194668 | biostudies-literature | 2011 May
REPOSITORIES: biostudies-literature
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