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IC‐02‐05: Rate of hippocampal atrophy is related to white matter atrophy and hypometabolism progression in mild cognitive impairment: A multimodal longitudinal study
Author(s) -
Chetelat Gaël,
Mézenge Florence,
Sayette Vincent,
Viader Fausto,
Baron Jean-Claude,
Eustache Francis,
Desgranges Béatrice
Publication year - 2008
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.2008.05.2485
Subject(s) - fornix , cingulum (brain) , atrophy , white matter , precuneus , grey matter , psychology , corpus callosum , neuroscience , posterior cingulate , hippocampus , cardiology , cognition , pathology , magnetic resonance imaging , medicine , fractional anisotropy , radiology
Background: There have been several longitudinal studies in patients with mild cognitive impairment (MCI) showing the progression of grey matter (GM) atrophy (mainly involving the hippocampus), and only one assessing the evolution of hypometabolism (highlighting the involvement of frontal and posterior cingulate (PCC) cortices). More recently, DTI studies have highlighted the alteration of white matter (WM) tracts, that more specifically concerned the cingulum, corpus callosum, fornix and perforant path, but there is no longitudinal study upon the evolution of WM alterations to date. In the present study, our aim was to assess the progression over time of GM and WM atrophy and hypometabolism in the same patients with MCI and their inter-relationships so as to better understand the evolving pathophysiological processes underlying early Alzheimer’s disease (AD). Methods: MRI-T1 and FDG-PET data were obtained in seventeen patients with MCI both at inclusion and eighteen months later. Grey matter (GM) and white matter (WM) data were obtained from the optimized VBM procedure while PET data were corrected for partial volume effect, spatially normalized, scaled (using the vermis as reference) and smoothed. Progression of GM and WM atrophy and hypometabolism was assessed by comparing baseline to follow-up data using paired t-tests in SPM2. Complementary correlative analyses were performed between-modality as well as with cognitive decline to better understand the relationships between these on-going changes and their impact on cognition. Results: The profiles of progression mainly involved the whole hippocampus for GM atrophy, the cingulum and fornix for WM atrophy, and the precuneus for hypometabolism. There was a significant positive relationship between the rate of hippocampal atrophy, alteration of the caudal part of the cingulum bundle, and metabolic decrease in the precuneus, that were significantly related to memory deficits. Conclusions: As a whole, this study highlights the on-going brain changes that accompany progression from MCI to AD. It suggests that the well known progression of hippocampal atrophy is paralleled by the disruption of its projection tract to the PCC, which may itself be involved in the progression of hypometabolism in the precuneus, these related changes being responsible for memory deficits in early AD.