Dynamic Functional Connectivity in MS Fatigue

Although global dynamic functional connectivity (dFC) was not associated with fatigue in patients with multiple sclerosis (MS), correlations were observed between lower dFC of the basal ganglia and the Default Mode Network (DMN) and fatigue.

Thirty-five patients with relapsing-remitting MS were compared with 19 healthy controls. In the MS group, the mean age was 42.83 years, mean disease duration was 11 years, and 20 patients were female. In the control group, the mean age was 41.38 years, and 11 patients were female. Patients self-reported fatigue at baseline and six months using the Checklist of Individual Strength questionnaire. Structural and resting-state functional MRI were conducted at baseline. The researchers calculated global static functional connectivity and dFC, and estimates were calculated for connectivity between regions that have previously been believed to be correlated with MS fatigue, including basal ganglia and regions of the DMN (medial prefrontal, posterior cingulate, and precuneal cortices).

Patients with MS, compared with controls, were more fatigued at baseline (P=0.001) and follow-up (P=0.002); patient fatigue was stable over time (P=0.213). Baseline global dFC was much higher among patients with MS, but baseline ganglia-DMN dFC did not differ between patients with MS and controls.

The regression model for baseline fatigue in patients found that basal ganglia-DMN dFC-coefficient of variation (cv; standardized β=–0.353) accounted for 12.5% variance in addition to the Expanded Disability Status Scale (P=0.032). Basal ganglia-DMN dFC-cv was higher in non-fatigued patients compared with controls, but basal ganglia-DMN dFC was similar between fatigued patients and controls.

“Increased dynamics in non-fatigued patients compared with healthy controls might represent a network organization that protects against fatigue or signal early network dysfunction,” the study authors concluded.