Alterations in static and dynamic functional network connectivity in subcortical vascular cognitive impairment

The current study integrated static (sFNC) and dynamic (dFNC) functional network connectivity to investigate the neurobiological mechanisms underlying alterations in static and dynamic functional network connectivity in subcortical vascular cognitive impairment (SVCI). We recruited 80 patients with SVCI (39 males, 41 females) and 83 healthy controls (HCs) (32 males, 51 females). Clinical and imaging data, including clinical history, neuropsychological assessments, and MRI scans, were collected. We analyzed sFNC changes using independent component analysis (ICA) with resting-state functional MRI data. Dynamic connectivity was examined using the sliding time window technique and cluster analysis to assess brain functional activity states and temporal properties. Differences in dFNC temporal properties (fractional occupancy, mean dwell time, and number of transitions) between groups were assessed with two-sample t-tests. Spearman correlation analyses were performed to explore relationships between sFNC and dFNC changes and cognitive function. In the sFNC analysis, the SVCI group showed significantly decreased interactions between the sensorimotor network (SMN) and visual network (VN), and between the left frontoparietal network (lFPN) and VN ( p  < 0.05), and both of which were associated with cognitive function ( p  < 0.05). In the dFNC analysis, brain functional activity was grouped into four highly structured functional connection states. The results revealed one strongly connected state dominated by reduced connectivity, two moderately connected states primarily characterized by connectivity reductions with minor increases, and one weakly connected state with a modular pattern. These findings illustrate the progression in SVCI from connectivity disruption to compensation, eventually leading to a diminished compensatory response. Fractional occupancy and mean dwell time of states were correlated with cognitive function (all p  < 0.05). CSVD patients exhibit impairments in both sFNC and dFNC, linked to cognitive decline. Connectivity dynamics reflect the brain's adaptive capacity in response to cognitive impairment.