Fatigue May Have Negative Effect on Cognition in Patients With MS

Fatigue associated with multiple sclerosis (MS) impedes cognition, according to study results presented at the 2023 Consortium of Multiple Sclerosis Centers (CMSC) Annual Meeting, held from May 31 to June 3 in Aurora, Colorado.

Fatigue is a commonly reported adverse effect in individuals with MS, with up to 80% of patients affected. As cognition may also be affected, researchers aimed to quantify neuronal changes caused by fatigue in patients with MS via magnetoencephalography (MEG), which measures changes in magnetic brain waves before and after a cognitive task.

The researchers gathered MEG data on 9 patents with MS, compared with 5 control individuals using The Modified Fatigue Impact Scale (MFIS) and Symbol Digit Modalities Test (SDMT).

They used 4 different frequency bands to stratify data: theta (4-7 Hz), alpha (8-13 HZ), beta (14-30 Hz), and gamma (30-85 Hz). Strength of connectivity for each frequency was mapped in each hemisphere, resulting in 1,431 pairings in the brain. Wilcoxon tests were used to assess the associations between SDMT/MFIS and brain lesion locations.

The researchers found right frontotemporal and right frontal to occipital regions in control individuals had higher interhemispheric gamma activity. Additionally, control individuals had higher left, right, and interhemispheric beta activity in the frontal-temporal and frontal-occipital regions.

Of note, however, these associations were not considered statistically significant, owing to a small sample size as a major limitation.

The researchers noted that “In patients with MS compared with controls [control individuals], MEG was able to detect clear differences in active networks during SDMT tasks.” “Slow processing speed has been associated with reduced frontal lobe activation in younger adults. Our study cohort supported the lack of coherent beta activity in the frontal lobe,” they concluded.