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Lobar distribution of white matter abnormalities in Alzheimer’s, vascular and mixed dementias
Author(s) -
Lee Hyunwoo,
Wiggermann Vanessa,
Rauscher Alexander,
Beg Mirza Faisal,
Popuri Karteek,
Tam Roger,
Lam Kevin,
Jacova Claudia,
Sossi Vesna,
Pettersen Jacqueline,
Benavente Oscar R.,
Hsiung GingYuek Robin
Publication year - 2020
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 - 10.1002/alz.043934
Subject(s) - fluid attenuated inversion recovery , hyperintensity , dementia , cardiology , vascular dementia , medicine , white matter , cognitive decline , alzheimer's disease , magnetic resonance imaging , psychology , neuroscience , nuclear medicine , disease , radiology
Background Vascular dementia (VaD) is often difficult to distinguish from Alzheimer’s disease (AD). [O’Brien_2015] Areas of cognitive/clinical decline due to cerebrovascular diseases depend on the frequency and location of the lesions, and may overlap with those found in AD. [Suri_2014] Moreover, AD and cerebrovascular diseases frequently occur simultaneously, leading to heterogeneous ‘mixed dementia (MixD)’. [Wang_2012][Langa_2004] It is unclear whether the presence of both neurodegenerative and cerebrovascular pathologies further aggravates dementia‐related imaging abnormalities. We investigated whether the lobar distribution of white matter hyperintensities (WMHs) on MRI differed among AD, VaD and MixD. Method N=17 participants (cross‐sectional; subtypes:7 MixD/5 Subcortical VaD/5 AD; Sex: 11M/6F; Age: 75±8yrs) were scanned on a 3T Philips Achieva. T1‐weighted MP‐RAGE images were processed with Freesurfer 6.0. Areas of WMHs were segmented on Fluid Attenuated Inversion Recovery (3D‐FLAIR) images using a combination of intensity thresholding and manual correction. Left and right frontal, temporal, occipital and parietal lobes plus basal ganglia volumes were constructed using the Freesurfer segmentation outputs. Individual WMH masks were transformed to their respective T1‐weighted spaces, and the ratios of WMH volumes to different lobar volumes were calculated. Result Average WMH volumes were (mean±SD) AD: 5191±4693mm 3 , MixD: 34680±17059mm 3 (sig. greater than AD), SVaD: 20896±14920mm 3 (n.s. from MixD or AD). We used a linear model to predict the ratios of WMH to lobar volumes from the diagnosis subtypes, adjusting for age and sex. A significant diagnosis‐subtype effect was found in both the left and right frontal lobes. (p=0.012 and 0.045, respectively). In the left frontal lobe, the proportion of WMHs was significantly greater in the MixD subgroup compared to the AD (p=0.0045) or the VaD (p=0.026) subtypes. In the right frontal lobe, the proportion was greater in the MixD subtype compared to the AD (p=0.018) but not compared to VaD (p=0.074) subtype. AD vs. VaD were not significantly different in either sides (p=0.5). Conclusion The MixD subtype of our pilot study cohort was characterized by a significantly greater presence of WMHs in the frontal lobar areas. Future studies are warranted to investigate the characteristics of underlying tissue abnormalities that could be specific to the diagnosis subtypes.