Long-COVID brain changes detected by advanced MRI technology

Researchers at Linköping University have made significant strides in understanding the lingering neurological effects of COVID-19. Using advanced MRI technology, the team has uncovered notable differences in brain tissue structure between patients who have had severe COVID-19 and those who have not.

The study was focused on 16 patients who had been hospitalized due to COVID-19 and continued to experience symptoms. 

The research is a part of the larger Linköping COVID-19 Study (LinCos). It stands out from previous studies in its use of advanced diffusion MRI, a technique that is sensitive to the microstructural organization of the brain, particularly the white matter.

Detecting COVID-19 brain changes

White matter, primarily composed of nerve axons, is crucial for signal transmission within the brain and to the body. Traditional MRI scans have not been specific enough to detect COVID-19 related changes in the brain, leading to frustration among clinicians.

Ida Blystad is a neuroradiologist in the Department of Radiology at Linköping University Hospital and researcher affiliated with the Department of Health, Medicine and Caring Sciences at Linköping University and the Centre for Medical Image Science and Visualization (CMIV).

“It can be frustrating for me as a doctor when I understand that the patients have problems, but I can’t find an explanation because there’s nothing in the MRI scan to explain it,” said Blystad. “To me, this underlines the importance of trying other examination technologies to understand what’s happening in the brain in patients with persisting symptoms after COVID-19.”

Novel approach 

The researchers compared the advanced diffusion MRI technology used in this study to the flow of traffic in a city at night. Just as the movement of cars along roads reveals the presence of highways, tracking the movement of water molecules in the brain helps infer the structure of neural pathways. 

This method has been instrumental in diagnosing strokes and planning brain surgery, but its application in understanding post-COVID conditions marks a novel approach.

“Diffusion MRI is a very sensitive technology that allows changes in how the nerve axons are organised to be detected. This is one of the reasons why we wanted to use diffusion MRI to study the effects of COVID-19 on the brain that other imaging technologies might not pick up,” explained doctoral student Deneb Boito.

Changes in white matter

The experts compared the brain scans of the 16 previously hospitalized men with those of a healthy control group. The findings indicated differences in the white matter structure of the two groups, suggesting a potential cause for the neurological issues faced by the COVID-19 survivors. 

“The two groups differ when it comes to brain white matter structure. This can be one of the causes of the neurological problems experienced by the group that had suffered from severe COVID-19. It’s a result that’s in line with other studies that have shown changes to the brain’s white matter,” said Blystad.

“However, having examined only a small group of patients, we are cautious about drawing any major conclusions. With this technology, we’re not measuring the function of the brain, but its microstructure. To me, these findings are a sign that we must investigate long-term effects of COVID-19 in the brain using more advanced MRI technology than conventional MRI.”

Many questions remain

Despite the breakthrough, several questions remain unanswered. The researchers are particularly interested in whether different brain regions are affected differently and how these changes correlate with brain function and inter-regional communication. 

Furthermore, since the study provides only a snapshot in time, it’s unclear whether the observed brain differences are permanent or if they will resolve over time.

This pioneering research was funded by several institutions, including the Analytic Imaging Diagnostic Arena (AIDA), the ITEA/Vinnova project ASSIST, and the Wallenberg Center for Molecular Medicine at Linköping University. 

The study is published in the journal Brain Communications.

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