Selective Aberrant Functional–Structural Coupling of Multiscale Brain Networks in Subcortical Vascular Mild Cognitive Impairment / 神经科学通报·英文版

Subcortical vascular mild cognitive impairment (svMCI) is a common prodromal stage of vascular dementia. Although mounting evidence has suggested abnormalities in several single brain network metrics, few studies have explored the consistency between functional and structural connectivity networks in svMCI. Here, we constructed such networks using resting-state fMRI for functional connectivity and diffusion tensor imaging for structural connectivity in 30 patients with svMCI and 30 normal controls. The functional networks were then parcellated into topological modules, corresponding to several well-defined functional domains. The coupling between the functional and structural networks was finally estimated and compared at the multiscale network level (whole brain and modular level). We found no significant intergroup differences in the functional–structural coupling within the whole brain; however, there was significantly increased functional–structural coupling within the dorsal attention module and decreased functional–structural coupling within the ventral attention module in the svMCI group. In addition, the svMCI patients demonstrated decreased intramodular connectivity strength in the visual, somatomotor, and dorsal attention modules as well as decreased intermodular connectivity strength between several modules in the functional network, mainly linking the visual, somatomotor, dorsal attention, ventral attention, and frontoparietal control modules. There was no significant correlation between the altered module-level functional–structural coupling and cognitive performance in patients with svMCI. These findings demonstrate for the first time that svMCI is reflected in a selective aberrant topological organization in multiscale brain networks and may improve our understanding of the pathophysiological mechanisms underlying svMCI.

Relationships between 24-Hour Blood Pressures, Subcortical Ischemic Lesions, and Cognitive Impairment

BACKGROUND AND PURPOSE: The most important treatment for subcortical vascular dementia (SVaD) is controlling the blood pressure (BP). However, the few studies that have investigated the relationships between diurnal BP rhythm and subcortical ischemic vascular cognitive impairment have produced inconclusive results. In the study presented here, the 24-hour BP values of three groups of subjects-patients with subcortical vascular mild cognitive impairment (SvMCI), patients with SVaD, and normal controls-were compared using working criteria and 24-hour ambulatory BP (ABP) monitoring. METHODS: The subjects (42 patients with SVaD, 37 patients with SvMCI, and 30 controls) were selected according to the study's inclusion/exclusion criteria. All subjects underwent brain magnetic resonance (MR) imaging and MR angiography, detailed neuropsychological testing, and 24-hour ABP monitoring. RESULTS: The prevalence of nondippers differed markedly between the control group and both the SVaD and SvMCI groups. Loss of nocturnal dipping was significantly associated with SVaD [odds ratio (OR), 4.827; 95% confidence interval (CI), 1.07-12.05]. CONCLUSIONS: It was found that SVaD is associated with loss of nocturnal BP dipping combined with increased pulse pressure and systolic BP (SBP) variability. Correction of these factors could therefore be important in the prevention of SVaD, independent of measures used to reduce BP.