White Brain Matter Damage Linked to Social Cognitive Impairment in Multiple Sclerosis

Impairments in social cognition are a reality for some patients with multiple sclerosis (MS). In addition to physical disability, social cognitive impairments are the reason for job loss in 24% to 80% of patients, increased divorce rate, and problems with social communication.

In a study published in Neurology, investigators found that this impairment may be linked to subtle changes in brain matter.

Included in the study were 60 patients with MS and 60 healthy individuals of comparable age and education level. Among the patients with MS, 50 had the relapsing-remitting form and the remaining had secondary progressive MS. They had been diagnosed with the disease for an average of 11 years.

Each of the study participants were required to take a test to measure their Theory of Mind (ToM) Skills. ToM is the ability to attribute mental states—–such as beliefs, intents, desires, and knowledge––to oneself and others, and to understand that others have beliefs, desires, intentions, and perspectives that are different from one’s own.

One test consisted of patients being shown photographs of people’s eye along with 4 words describing their mental states, such as anxious or embarrassed. They were then asked to select the word that best describes the feelings of the individual in the photo. In a different test, silent video clips of people interacting were shown to the participants along with 2 words that described the interaction. Again, they were asked to choose the best word.

MRI brain scans and diffusion tensor imaging were also conducted to assess for changes in white brain matter.

The results of the study showed that patients with MS had lower scores on both ToM tests. On the photo test, participants with MS had an average score of 59% compared with an average of 82% among the healthy participants. On the video tests, MS patients had an average of 75% compared with 88% for the controls.

These results were not related to how long the participants had MS, but rather the total volume of T1 and T2 lesions, the authors noted.

Brain scans revealed that patients with MS had widespread abnormalities in their white matter compared with healthy participants. The most extensive damage was found in the uncinated fasciculus, fornix, and corpus callosum—–which plays a key role in the social brain network.

The more damage that appeared in these areas of the brain, the more likely the patients were to have low scores on the social tests.

“It appears that there is a disconnect in the social brain network,” said investigator Sonia Batista, MD.

A limitation to the study was that the scans and tests were not all conducted at once, meaning any changes over time in social test scores or areas of brain damage were unable to be assessed.

“Understanding how MS affects the ‘social brain’ has not been well studied, but the ability to interpret other people’s feelings and intentions may influence people’s ability to maintain a job and their relationships with family and friends,” Batista said. “These skills are very important for people with MS since having good support is one of the main factors in whether people have a good quality of life.”

Although the findings provide more clues about MS, the authors noted that more research needs to be done to gain a deeper understand of these social issues in MS, including whether different forms of MS are affected differently, how the problems affect patients in their daily lives, and whether cognitive social impairment is linked to, or separate from, other issues with memory and thinking skills that occur in MS.