Distance-dependent Functional Connectivity Strength Analysis Using Resting-State fMRI: Application to Vascular Cognitive Impairment, No Dementia.

We present a resting-state fMRI-based protocol for quantifying anatomical distance-dependent functional connectivity strength (FCS) and demonstrate its application in vascular cognitive impairment, no dementia (VCIND). Resting-state fMRI data from VCIND patients and demographically matched normal controls were analyzed using voxel-wise FCS across six anatomical distance intervals to characterize short-, medium-, and long-range functional connectivity. Network-level analyses were also performed to identify large-scale network involvement. The results reveal a hierarchical distance-dependent organization of functional connectivity, with short-range connectivity concentrated in primary sensory systems and long-range connectivity increasingly involving higher-order association networks. In VCIND, significant alterations were observed particularly within the frontoparietal network, suggesting compensatory network reorganization associated with cognitive performance. These distance-dependent FCS alterations may serve as potential neuroimaging markers for early identification and risk stratification of VCIND and may also support longitudinal monitoring of functional network changes.