Abnormal dynamics of functional connectivity density and effective connectivity in overactive bladder.

Purpose: The study aims to analyze alterations in dynamic functional connectivity density (dFCD) and effective connectivity (dEC) patterns using functional magnetic resonance imaging (fMRI), hypothesizing that overactive bladder (OAB) patients will exhibit distinct dFCD and dEC patterns, reflecting altered neural communication underlying the OAB.

Methods: Forty-three female OAB patients and 40 female healthy controls (HC) underwent resting-state fMRI. Sliding window correlation was used to calculate the variability of the dFCD. The changes in dFCD-based dEC between the two groups were examined using Granger causal analysis. To describe the time-varying Granger causality, a sliding-window approach was utilized to divide time courses into a group of windows. We adopted a k-means clustering method to cluster all matrices into discrete connectivity states.

Results: Compared with HC, OAB females consistently had a dFCD (decreased) in the left anterior cingulate cortex (ACC) and left medial prefrontal cortex (mPFC) (p < 0.05, GRF corrected). In state 1, OAB patients had excitatory effective connections from bilateral ACC to left mPFC in comparison to HC. In state 2, there was an increase in dEC from the SMA to the mPFC. Participants with OAB showed significantly more inhibitory dorsolateral prefrontal cortex (dlPFC) connections between the left ACC and the right ACC in state 4, as well as an excitatory dEC connection between the right dlPFC and the left ACC in state 2 (p < 0.05, GRF corrected).

Conclusion: OAB patients demonstrate significant alterations in dFCD and dEC patterns, which may be indicative of the neural mechanisms involved in OAB pathophysiology.