Multiple brain networks support processing speed abilities of patients with multiple sclerosis

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Multiple sclerosis (MS) frequently causes cognitive impairment, particularly affecting information processing speed (PS).
• Neural disconnection is a suspected marker, but the role of specific functional brain networks remains unclear.

Purpose of the Study:

• To investigate and compare associations between processing speed (PS)-demanding cognitive performance and functional brain network connectivity.
• To examine these associations across two distinct multiple sclerosis (MS) phenotypes: relapsing-remitting MS (RRMS) and secondary progressive MS (SPMS).

Main Methods:

• Neuropsychological and MRI assessments were conducted on 40 RRMS and 25 SPMS patients.
• Multiple regression models analyzed the relationship between cognitive performance (visuomotor/verbal PS, verbal fluency) and functional connectivity in cognitive (frontoparietal, salience, default-mode) and control (visual, sensorimotor) networks.

Main Results:

• SPMS patients were older, had longer disease duration, and exhibited worse clinical status and higher cognitive impairment rates than RRMS patients.
• In both RRMS and SPMS groups, cognitive performance negatively correlated with salience and default-mode network connectivity and positively with left frontoparietal network connectivity.
• Visuomotor processing speed in the RRMS group also showed an association with sensorimotor network connectivity.

Conclusions:

• Processing speed (PS) in multiple sclerosis (MS) patients is primarily associated with the functional connectivity strength of frontal networks and the default mode network.
• These findings support the hypothesis that multiple neural networks are essential for maintaining cognitive function across different MS phenotypes.
• Partially differing associations between specific PS measures and functional connectivity warrant further research into inter-network communication's role in MS-related cognitive deficits.