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MS brain scans help to understand COVID impact

Long period of data imaging for MS patients gives unique insight into change in brains



Brain scans of people with Multiple Sclerosis are helping medical teams to better understand the impact of COVID-19. 

People living with MS undergo regular MRI brain scans and routinely have their brains checked at least once a year with an MRI scan to monitor the progression of the condition, so their brains are well documented prior to the onset of the pandemic in 2020. 

This data is proving valuable in understanding the full impact of COVID-19, as it provides the evidence to detect changes in the brain and comparable data exists to compare through the collection of imaging over time. 

“The large number of scans enables us to compare a person’s brain before and after a COVID-19 infection,” says biomedical engineer Michael Rebsamen, a PhD student at the University Institute for Diagnostic and Interventional Neuroradiology in Bern. 

He adds that this kind of longitudinal study of individuals is potentially far more useful than previous studies which compared MRI images of groups of healthy people to those of COVID-19 patients.

To assess the feasibility of this type of analysis, the researchers have so far evaluated 113 MRI brain scan images for 14 MS patients at the Inselspital in Bern who have had a SARS-CoV-2 infection. 

For the study, the researchers selected people whose MS condition remained stable during the relevant time period – this meant that any changes detected in the brain should not have been caused by a MS relapse. 

For the analysis, the researchers measured the volume of different brain regions over the course of several years right up to and then a few months after a COVID-19 infection.

The analysis showed that the grey matter volume remained constant overall. But one particular cortical region, the parahippocampal gyrus, was found to be statistically smaller following a COVID-19 infection. 

This regional change had little impact on the overall volume owing to its small size. 

As the parahippocampal gyrus region of the brain is associated with smell and memory, among other functions, there is a hypothetical link to the sense of smell and memory losses commonly associated with a COVID-19 infection. The mechanism by which the SARS-CoV-2 virus leads to these changes is the subject of ongoing research.

The preliminary study and its small number of participants does not yet provide a sufficient basis for drawing definite conclusions. 

“But worldwide there is a vast volume of imaging data for MS patients,” says Rebsamen. 

Analysing this material could make it possible to look much more specifically at the causal links – to assess, for example, whether the severity of a COVID-19 infection makes a difference, or whether the same changes to the brain structure occur in vaccinated and unvaccinated people.

“The big question is also whether the changes that have been measured are reversible or if they persist,” says Rebsamen. 

“Our focus was on the first few months after infection.” 

A longer period of observation in a larger study could show what occurs in the brain during Long COVID, as this is often associated with a negative impact on cognitive functions.