Abstract
Patients with subcortical ischemic vascular disease (SIVD) exhibit a high risk of cognitive impairment that might be caused by neurologic deficits and vascular injuries. However, the mechanism remains unknown. In current study, 24 normal controls (NC) and 54 SIVD patients, including 26 SIVD patients with no cognitive impairment (SIVD-NCI) and 28 SIVD patients with mild cognitive impairment (SIVD-MCI) underwent the resting-state functional MRI (rs-fMRI) and neuropsychological assessments. We combined regional homogeneity (ReHo) and cerebral blood flow (CBF) by using the global ReHo-CBF correlations coefficient and the ReHo/CBF ratio to detect the inner link between neuronal activity and vascular responses. Correlations between the ReHo/CBF ratio and neuropsychological assessments were explored in patients with SIVD. As a result, we identified significantly decreased global ReHo-CBF coupling in the SIVD-NCI group and SIVD- MCI group with respect to the NC. The SIVD-MCI group showed more serious decoupling of the global ReHo-CBF correlation. We also found a significantly abnormal ReHo/CBF ratio predominantly located in cognitive-related brain regions, including the left insula, right middle temporal gyrus, right precuneus, left precentral gyrus, and left inferior parietal lobule but not the supramarginal and angular gyri. The SIVD-MCI group showed more severe disorders of neurovascular coupling than the other two groups. Moreover, the ReHo/CBF ratio in the left precentral gyrus of the SIVD-NCI group exhibited a positive correlation with the MMSE scores. These findings suggested that patients with SIVD show abnormal neurovascular coupling at the early stage of the disease and during disease development. It might be associated with disease severity and cognitive impairment. Neurovascular decoupling in brain may be a possible neuropathological mechanism of SIVD.
Highlights
Subcortical ischemic vascular disease (SIVD) is a devastating illness with unclear etiology
We found that the mean values of regional homogeneity (ReHo)/cerebral blood flow (CBF) ratio at the PreCG.L in subcortical ischemic vascular disease (SIVD)-NCI group exhibited a positive correlation with MiniMental State Examination (MMSE) scores (r = 0.55, P = 0.006)
CBF was significantly correlated with ReHo in three groups, the SIVD patients had reduced global ReHo–CBF coupling relative to the normal controls (NC) group
Summary
Subcortical ischemic vascular disease (SIVD) is a devastating illness with unclear etiology. As the most common type of cerebral smallvessel disease (CSVD), SIVD may be related to the damaged endothelial cells, abnormal perfusion, and disrupted structural and functional connections in the brain (Wallin et al, 2018; Thrippleton et al, 2019). These alterations can promote the dysregulation of the neurovascular unit (NVU) which comprised neurons, astrocytes, and vessels (Muoio et al, 2014). CSVD could disturb this coupling and lead to incongruities between the cerebral blood supply and neuronal activity which might be treated as the main cause of cognitive impairment, but the mechanisms still cannot be fully explained (Caruso et al, 2019; Moretti and Caruso, 2020)
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