Abstract
Changes in white matter (WM) microstructure may relate to the pathophysiology of cognitive impairment. Whether WM microstructure differs in two common pre-dementia subtypes, vascular mild cognitive impairment (VaMCI) and amnestic mild cognitive impairment (aMCI), is largely unknown. This study included 28 VaMCI (12 men, age: 46 ~ 77 years) and 34 aMCI patients (14 men, age: 51 ~ 79 years). All patients underwent a battery of neuropsychological tests and structural and diffusion magnetic resonance imaging (MRI) scanning. WM microstructure was quantified using diffusion MRI parameters: fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AxD) and radial diffusivity (RD). These parameters were compared between the two patient groups using tract-based spatial statistics (TBSS) after controlling for age, gender, and education. No significant differences in FA/MD/AxD/RD were observed between the VaMCI and aMCI groups, which suggests a similar pattern of WM microstructure in the early stage of cognitive impairment for different dementia types. However, the two groups exhibited significant differences in the relationship between FA and the Auditory Verbal Learning Test (AVLT), which were primarily located around the corona radiate and corpus callosum. Specifically, there were significant positive correlations (R = 0.64, P < 0.001) between the FA and AVLT in the VaMCI group, but the opposite trend was observed in the aMCI group (R = −0.34, P = 0.047). The differential relationship between WM and memory between VaMCI and aMCI indicates an independent neuropathology for specific memory deficits in different types of dementia.
Highlights
Vascular cognitive disorders (VCD) represent a wide spectrum of cognitive disorders associated with vascular causes, including vascular mild cognitive impairment (VaMCI) and vascular dementia (VD)
No significant differences in fractional anisotropy (FA)/mean diffusivity (MD)/axial diffusivity (AxD)/radial diffusivity (RD) were observed between the VaMCI and amnestic mild cognitive impairment (aMCI) groups, which suggests a similar pattern of white matter (WM) microstructure in the early stage of cognitive impairment for different dementia types
The present study examined whether WM microstructure differed between VaMCI and aMCI by directly comparing two groups of age-matched patients and whether the relationships between WM and cognition differed between the two groups using diffusion magnetic resonance imaging (MRI) data combined with the tractbased spatial statistics (TBSS) method
Summary
Vascular cognitive disorders (VCD) represent a wide spectrum of cognitive disorders associated with vascular causes, including vascular mild cognitive impairment (VaMCI) and vascular dementia (VD). VaMCI is defined as the prodromal stage of VD [1, 2]. Another common mild cognitive impairment (MCI) is amnestic MCI (aMCI), which represents the prodromal stage of Alzheimer’s disease (AD) [3]. VaMCI and aMCI are highly prevalent MCI subtypes, and both conditions are associated with deficits in multiple cognitive domains, with identical chief complaints in memory deficits [4, 5]. Whether differences in WM impairments appear at very early stages of these two main dementia subtypes is not known
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