The role of disturbed small-world networks in patients with white matter lesions and cognitive impairment revealed by resting state function magnetic resonance images (rs-fMRI)

Background: Leukoaraiosis is characterized by white matter lesions (WMLs) on magnetic resonance imaging (MRI) and is associated with cognitive impairment. The small-world network is viewed as the optimal brain network with maximal efficiency in information processing. Patients with cognitive impairment are thought to have disrupted small-world networks. In this study, we compared the small-world network attributes between controls (study participants without memory complaints) and patients with WMLs with cognitive impairment. Material/Methods: All study participants were prescreened using MRI and neuropsychological tests. Patients with WMLs were further divided into 2 groups according to the result of Montreal Cognitive Assessment (MoCA), i.e., WMLs with non-dementia vascular cognitive impairment (WMLs-VCIND) and WMLs with vascular dementia (WMLs-VaD). Resting-state functional MRI data were collected and applied with graph theoretical analysis to compare small-world properties between the 3 groups. Results: We found that the overall functional connectivity strength was lowest in the WMLs-VaD patients but highest in the normal control study participants. Patients in both the WMLs-VCIND and the WMLs-VaD groups had decreased small-world properties compared with the group of normal control study participants. Moreover, the small-world properties significantly correlated with MoCA scores. Conclusions: These findings suggest potential constructive reorganization of brain networks secondary to WMLs, and provides novel insights into the role of small-world properties in cognitive dysfunction in WMLs.