White matter damage of patients with Alzheimer’s disease correlated with the decreased cognitive function

Abstract

Increasing evidence demonstrates that there is marked damage and dysfunction in the white matter in Alzheimer's disease (AD). The present study investigates the nature of white matter damage of patients with Alzheimer's disease with diffusion tensor magnetic resonance imaging (DTI) and analyses the relationship between the white matter damage and the cognition function. DTI, as well as T1 fluid attenuated inversion recovery (FLAIR) and T2-FLAIR, was performed on probable patients of Alzheimer's disease, and sex and age matched healthy volunteers to measure the fractional anisotropy (FA) and mean diffusivity (MD) in the genu and splenium of the corpus callosum, anterior and posterior limbs of the internal capsule, and the white matter of frontal, temporal, parietal, and occipital lobes. FA was lower in the splenium of corpus callosum, as well as in the white matter of the frontal, temporal, and parietal lobes from patients with Alzheimer's disease than in the corresponding region from healthy controls and was strongly positive correlated with MMSE scores, whereas FA appeared no different in the anterior and posterior limbs of internal capsule, occipital lobes white matter, and the genu of corpus callosum between the patients and healthy controls. MD was significantly higher in the splenium of corpus callosum and parietal lobes white matter from patients than in that those from healthy controls and was strongly negative correlated with MMSE scores, whereas MD in the anterior and posterior limbs of internal capsule, as well as in frontal, temporal, occipital lobes white matter and the genu of corpus callosum, was not different between the patients and healthy controls. The most prominent alteration of FA and MD was in the splenium of corpus callosum. Our results suggested that white matter of patients with Alzheimer's disease was selectively impaired and the extent of damage had a strong correlation with the cognitive function, and that selective impairment reflected the cortico-cortical and cortico-subcortical disconnections in the pathomechanism of Alzheimer's disease. The values of FA and MD in white matter, especially in the splenium of corpus callosum in AD patients, might be a more appropriate surrogate marker for monitoring the disease progression.

Diffusion Tensor Imaging of Normal-Appearing White Matter in Mild Cognitive Impairment and Early Alzheimer Disease: Preliminary Evidence of Axonal Degeneration in the Temporal Lobe

“…These results agree with our current understanding of relationships between brain regions and domains of cognitive function and reveal a pattern of poorer cognitive test performance in association with loss of anisotropic diffusion. [42][43][44][45] Our study has several limitations. The small sample size limits the power of this pilot investigation.…”

In Vivo Structural Neuroanatomy of Corpus Callosum in Alzheimer's Disease and Mild Cognitive Impairment Using Different MRI Techniques: A Review

“…DTI studies on AD "all stages" patients [32,35,36,39,41,79,80] basically found changes in the anterior (genu) and posterior (splenium) subregions of the CC in AD patients compared with HC. More specifically, Rose et al [32] found a value reduction in the splenium of AD patients but not in HC.…”

“…The other studies that measured MD and/or FA can be separated into those which found mainly an increase of MD and/or a decrease of FA in the posterior subregion (splenium) of the CC in AD [35,36,41,79,80] and those which reported an increase in MD or a decrease in FA in the anterior subregions (genu and anterior body) of CC in AD compared with HC [35,39]. It is very difficult to summarize the general picture of these results because other studies on AD "all stages" [23,37,40,75] reported no significant differences in MD or FA in the anterior and posterior CC when the patient group was compared with HC.…”

Assessing neuronal networks: Understanding Alzheimer's disease

“…Based on the assumption that the diffusivity is maximal in the direction of fibre tracts, the voxelby-voxel determination of FA can be used in order to tract fibres at the macroscopic level (Mori and van Zijl, 2002). A number of DTI-based studies in AD patients have (Hanyu et al, 1998;Kantarci et al, 2001), anterior and posterior cingulate gyrus (Kantarci et al, 2001;Rose et al, 2000;Takahashi et al, 2002;Zhang et al, 2007), and the corpus callosum (Bozzali et al, 2002;Duan et al, 2006;Sydykova et al, 2006;Teipel et al, 2007b;Xie et al, 2006). hypothesis that the changes produced by AD neuropathology within the brain follow a network of connections that arise from the medial temporal areas (Arriagada et al, 1992a;Morrison and Hof, 2002;Morrison et al, 1986).…”