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Hum Brain Mapp. 2017 Apr;38(4):1791-1800. doi: 10.1002/hbm.23482. Epub 2016 Dec 16.

Distinct white matter injury associated with medial temporal lobe atrophy in Alzheimer's versus semantic dementia.

Bejanin A1,2,3,4, Desgranges B1,2,3,4, La Joie R1,2,3,4, Landeau B1,2,3,4, Perrotin A1,2,3,4, Mézenge F1,2,3,4, Belliard S1,2,3,5, de La Sayette V1,2,3,4,6, Eustache F1,2,3,4, Chételat G1,2,3,4.

Author information

1
U1077, Inserm, Caen, France.
2
UMR-S1077, Université de Caen - Normandie, Caen, France.
3
UMR-S1077, Ecole Pratique des Hautes Etudes, Caen, France.
4
U1077, CHU de Caen, Caen, France.
5
Service de Neurologie, CHU Pontchaillou, Rennes, France.
6
Service de Neurologie, CHU de Caen, Caen, France.

Abstract

This study aims at further understanding the distinct vulnerability of brain networks in Alzheimer's disease (AD) versus semantic dementia (SD) investigating the white matter injury associated with medial temporal lobe (MTL) atrophy in both conditions. Twenty-six AD patients, twenty-one SD patients, and thirty-nine controls underwent a high-resolution T1-MRI scan allowing to obtain maps of grey matter volume and white matter density. A statistical conjunction approach was used to identify MTL regions showing grey matter atrophy in both patient groups. The relationship between this common grey matter atrophy and white matter density maps was then assessed within each patient group. Patterns of grey matter atrophy were distinct in AD and SD but included a common region in the MTL, encompassing the hippocampus and amygdala. This common atrophy was associated with alterations in different white matter areas in AD versus SD, mainly including the cingulum and corpus callosum in AD, while restricted to the temporal lobe - essentially the uncinate and inferior longitudinal fasciculi - in SD. Complementary analyses revealed that these relationships remained significant when controlling for global atrophy or disease severity. Overall, this study provides the first evidence that atrophy of the same MTL region is related to damage in distinct white matter fibers in AD and SD. These different patterns emphasize the vulnerability of distinct brain networks related to the MTL in these two disorders, which might underlie the discrepancy in their symptoms. These results further suggest differences between AD and SD in the neuropathological processes occurring in the MTL. Hum Brain Mapp 38:1791-1800, 2017.

KEYWORDS:

Alzheimer's disease; hippocampus; medial temporal lobe; primary progressive aphasia; semantic dementia; white matter

PMID:
27981671
DOI:
10.1002/hbm.23482
[Indexed for MEDLINE]

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