Examination of processing speed deficits in multiple sclerosis using functional magnetic resonance imaging

Area of Science:

• Neuroscience
• Cognitive Neurology
• Neuroimaging

Background:

• Processing speed deficits are a hallmark cognitive impairment in multiple sclerosis (MS).
• The specific neural mechanisms underlying these processing speed impairments in MS are not well understood.
• Understanding these mechanisms is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate the differences in brain activity during a processing speed task between individuals with MS and healthy controls (HCs).
• To identify the neural networks associated with processing speed in both MS and HC groups.
• To compare the neural underpinnings of processing speed deficits in MS to those observed in aging.

Main Methods:

• BOLD functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• 16 individuals with MS and 17 HCs performed a modified Symbol Digit Modalities Task.
• Group comparisons of brain activation patterns and network mediation were analyzed.

Main Results:

• The MS group exhibited significantly slower performance compared to HCs, with no difference in accuracy.
• MS patients showed reduced cerebral activity in bilateral frontal and parietal regions compared to HCs.
• Neural networks mediating processing speed differed, with HCs relying on frontal, parietal, cerebellum, and thalamus, while MS relied on insula, thalamus, and anterior cingulate.

Conclusions:

• Neural network differences in processing speed exist between individuals with MS and HCs.
• The observed alterations in MS resemble neural patterns seen in aging, potentially linked to white and gray matter damage.
• These findings highlight distinct neural substrates for processing speed in MS, suggesting unique compensatory or pathological mechanisms.