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P1‐458: LEVEL OF BRAIN RESERVE ASSOCIATED WITH SPATIAL EXTENT OF TAU‐NEURODEGENERATION PATTERN IN ALZHEIMER'S DISEASE
Author(s) -
Hönig Merle C.,
Bischof Gerard N.,
Kukolja Juraj,
Jessen Frank,
Neumaier Bernd,
Drzezga Alexander,
Eimeren Thilo
Publication year - 2018
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2018.06.468
Subject(s) - neurodegeneration , statistical parametric mapping , voxel , correlation , white matter , grey matter , tau pathology , nuclear medicine , alzheimer's disease , medicine , partial volume , pathology , neuroscience , disease , psychology , magnetic resonance imaging , radiology , mathematics , geometry
Cognitive impairment (MCI) (15 multiple-domain) and of 20 Alzheimer’s disease (AD) patients were analysed and correlated with cognitive scores. Cerebral blood flow (CBF) maps obtained from ASL scans were first co-registered with the T2-weighted scans and then with the T1-weighted scans. Partial volume correction was performed, assuming that the perfusion in white matter is globally 40% of that of grey matter (GM). An Independent component analysis based approach was adopted for the analysis of RS fMRI scans. Results: AD patients, compared to both MCI and Controls, showed a significant decrease in ASL signal in the inferior parietal lobule, parieto-occipital area and precuneus bilaterally. These regions mostly overlap with the posterior part of the default mode network. The MCI group when compared with controls showed an increase in blood flow in Brodmann areas 17, 18, 19, occipital lobe and lobule 6 of the cerebellum. Interestingly, in MCI patients, a statistically significant negative correlation was found between the performance in the letter fluency test and the CBF signal in the Lobule 6 of the cerebellum (p1⁄40.04); in the same area of the cerebellum a positive correlation was found between letter fluency test performance and BOLD signal (p1⁄40.025). Conclusions: The ASL findings suggest that the increases in blood flow observed in the MCI group might reflect compensatory processes, at a stage when patients still have sufficient cognitive reserve to draw on. However, the negative correlation observed for the letter fluency task does not support this interpretation. Since the cerebellum has a well established connectivity with the frontal cortex, it is postulated that it might take charge of residual cognitive performance in MCI. Nevertheless, this process does not appear compensatory but is the outcome of a maladaptive process that responds to CBF decreases with increases in functional connectivity to support cognitive function.