Patients with Mild Cognitive Impairment May be Stratified by Advanced Diffusion Metrics and Neurocognitive Testing

Abstract

BACKGROUND AND PURPOSE Mild cognitive impairment (MCI) is a prevalent disorder, with a subset of patients progressing to dementia each year. Although MCI may be subdivided into amnestic or vascular types as well as into single or multiple cognitive domain involvement, most prior studies using advanced diffusion imaging have not accounted for these categories. The purpose of the current study was to determine if the pattern of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) metrics in patients with amnestic MCI (aMCI) correlate to specific cognitive domain impairments. METHODS Nineteen consecutive patients with aMCI referred for brain magnetic resonance imaging (MRI) were included. All subjects underwent neurocognitive testing. A z‐score was calculated for each domain and a composite of all four domains. Brain MRI included standard structural imaging and diffusion imaging. Volumetric, DTI, and DKI metrics were calculated and statistical analysis was performed with adjustments for multiple measures and comparisons. RESULTS Statistically significant correlations between diffusion metrics and cognitive z‐scores were detected: visuospatial‐visuoconstructional z‐scores only correlated with alterations in the corpus callosum splenium, executive functioning z‐scores with the corpus callosum genu, memory testing z‐scores with the left hippocampus, and composite z‐scores with the anterior centrum semiovale. CONCLUSION Neuroimaging studies of patients with aMCI to date have assumed a population with homogeneous cognitive impairment. Our results demonstrate selective patterns of regional diffusion metric alterations correlate to specific cognitive domain impairments. Future studies should account for this heterogeneity, and this may also be useful for prognostication.

Microstructural changes in the cingulate gyrus of patients with mild cognitive impairment induced by cerebral small vessel disease

“…In addition, increased values for MD, AD, and RD and decreased FA, MK, AK, and RK were observed in the corpus callosum, bilateral cingulate bundle, bilateral temporal and frontal regions of patients with early AD [20]. According to a previous study, the FA and MK values of DKI are usually reduced due to microstructure damage to the cingulate cortex [8]. [21].…”

“…In previous studies, microstructural changes in patients with MCI have been observed using diffusion tensor imaging (DTI). Two of the most widely reported DTI metrics, fractional anisotropy (FA) and mean diffusion (MD), are altered in multiple white matter tracts of patients with MCI [8,9]. Diffusion kurtosis imaging (DKI) extends conventional DTI measures by detecting microstructural changes not only in white matter (WM, anisotropic tissues) but also in gray matter (GM, isotropic tissues) because it is independent of the spatial direction of the structures [10].…”

Diffusion kurtosis imaging of brain white matter alteration in patients with coronary artery disease based on the TBSS method

“…At present, we have not found any articles specifically discussing the relationship between DKI and CI in CAD patients. However, a study on a population with pure cognitive impairment found that DKI metrics were closely related to cognitive function scores in regions such as the posterior limb of the internal capsule ( Allen et al, 2019 ). This finding is consistent with our research results.…”

Docetaxel-induced cognitive impairment in rats can be ameliorated by edaravone dexborneol: Evidence from the indicators of biological behavior and anisotropic fraction

“…When the integrity of white matter fibers is damaged, the dispersion barrier is damaged, resulting in weakening of the dispersion ability of water molecules along the direction of white matter fiber bundles, together with enhancement of the dispersion ability to the periphery, and consequently, FA value is decreased. Many studies have also shown that the FA value of the hippocampus is generally reduced in patients with mild cognitive impairment ( Zhao et al, 2014 ; Allen et al, 2019 ). The fornix is composed of output fibers of the hippocampus and is an important structure that maintains its normal function.…”