Global functional connectivity reorganization reflects cognitive processing speed deficits and fatigue in multiple...

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Neurology

Background:

• Cognitive impairment (CI) in multiple sclerosis (MS) is linked to brain network changes.
• Current functional magnetic resonance imaging (fMRI) biomarkers for CI in MS are limited.
• Resting-state centrality measures show bidirectional changes in MS-related CI.

Purpose of the Study:

• To evaluate the graph-theory-based degree rank order disruption index (kD) as a potential fMRI biomarker for CI in MS.
• To assess the association between kD and cognitive processing speed in patients with MS (PwMS).
• To compare kD's efficacy against established imaging biomarkers for CI in MS.

Main Methods:

• A secondary cross-sectional fMRI analysis was performed on 56 PwMS and 58 healthy controls (HCs).
• The kD index was calculated and compared between PwMS and HCs.
• kD's correlation with cognitive function (Symbol Digit Modalities Test), fatigue, gait, and disability was assessed and compared to other biomarkers.

Main Results:

• PwMS exhibited significantly lower kD values compared to HCs (p=0.009).
• kD and medial prefrontal cortex (MPFC) degree showed significant correlations with cognitive impairment (p=0.019 and p=0.001, respectively).
• kD also correlated with fatigue (p=0.010) but not with gait or global disability.

Conclusions:

• The kD index demonstrates potential as a novel fMRI biomarker for cognitive impairment in MS.
• kD may also serve as a biomarker for fatigue in patients with MS.
• Further research and validation are warranted to establish kD's clinical utility.