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 AND 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.