Midlife measurements of white matter microstructure predict subsequent regional white matter atrophy in healthy adults - PubMed (original) (raw)

. 2014 May;35(5):2044-54.

doi: 10.1002/hbm.22311. Epub 2013 Jul 17.

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Midlife measurements of white matter microstructure predict subsequent regional white matter atrophy in healthy adults

Martina Ly et al. Hum Brain Mapp. 2014 May.

Abstract

Objectives: Although age-related brain changes are becoming better understood, midlife patterns of change are still in need of characterization, and longitudinal studies are lacking. The aim of this study was to determine if baseline fractional anisotropy (FA), obtained from diffusion tensor imaging (DTI) predicts volume change over a 4-year interval.

Experimental design: Forty-four cognitively healthy middle-age adults underwent baseline DTI and longitudinal T1-weighted magnetic resonance imaging. Tensor-based morphometry methods were used to evaluate volume change over time. FA values were extracted from regions of interest that included the cingulum, entorhinal white matter, and the genu and splenium of the corpus callosum. Baseline FA was used as a predictor variable, whereas gray and white matter atrophy rates as indexed by Tensor-based morphometry were the dependent variables.

Principal observations: Over a 4-year period, participants showed significant contraction of white matter, especially in frontal, temporal, and cerebellar regions (P < 0.05, corrected for multiple comparisons). Baseline FA in entorhinal white matter, genu, and splenium was associated with longitudinal rates of atrophy in regions that included the superior longitudinal fasciculus, anterior corona radiata, temporal stem, and white matter of the inferior temporal gyrus (P < 0.001, uncorrected for multiple comparisons).

Conclusions: Brain change with aging is characterized by extensive shrinkage of white matter. Baseline white matter microstructure as indexed by DTI was associated with some of the observed regional volume loss. The findings suggest that both white matter volume loss and microstructural alterations should be considered more prominently in models of aging and neurodegenerative diseases.

Keywords: aging; atrophy; diffusion tensor imaging; fractional anisotropy; longitudinal; microstructure; tensor-based morphometry.

Copyright © 2013 Wiley Periodicals, Inc.

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Figures

Figure 1

Figure 1

White matter ROIs (shown in red) overlayed on the FA template image (skeletonized FA underlayed in light gray). The bilateral ROIs included: (A) cingulum bundle subjacent to posterior cingulate (119 voxels, MNI coordinates: ±11,−45, 28), (B) cingulum adjacent to hippocampus (60 voxels, MNI coordinates: ±20, −42, −2), (C) entorhinal white matter (96 voxels, MNI coordinates: ±24, −26, −19), (D) corticospinal tract (31 voxels, MNI coordinates: ±10, −20, −24), (E) splenium (49 voxels, MNI coordinates: ±1, −35, 14), and (F) genu (48 voxels, MNI coordinates: ±4, 23, −1) of the corpus callosum. (A–C) Sagittal view, (D) coronal view, and (E, F) an axial view.

Figure 2

Figure 2

Regions of tissue contraction for more than 4 years (P < 0.05, FWE corrected). As shown in the 3D render (A) and sagittal cross‐section (B), there was significant contraction in temporal stem white matter for more than 4 years. Additionally, as shown in the coronal sections (C), there was significant contraction in large portions of bilateral subcortical white matter and the cerebellum. The color bar represents _T_‐values.

Figure 3

Figure 3

Regions (A) where baseline FA from the splenium (green), entorhinal white matter (orange), and genu (blue) predict volume loss from baseline to follow‐up (P < 0.001, uncorrected). The statistical map is overlaid on coronal sections of the “CH2” template available in MRIcron (Rorden, 2007). The correlation between (B) baseline splenium FA and cerebellar hemisphere volume loss was r 2 = 0.25, P < 0.001 and (C) baseline genu FA and inferior temporal gyrus WM volume loss was r 2 = 0.33, P < 0.001. Data points represent individual participants. [Color figure can be viewed in the online issue, which is available at

http://wileyonlinelibrary.com

.]

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