Researchers at Linköping University in Sweden analyzed the brains of 16 people who had previously been hospitalized for Covid-19 and still had symptoms. They found changes in the structure of brain tissue between patients who had persistent symptoms after contracting Covid-19 and healthy people. Their findings, which were published in the journal Brain Communications, may shed light on the underlying causes of neurological disorders that persist after Covid-19.
Several previous studies of ongoing post-Covid problems have involved MRI scans of the brain. Although the researchers found differences compared to healthy brains, these differences were not specific to Covid-19.
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“It can be frustrating for me as a doctor when I understand that patients have problems but I can’t find an explanation because there is nothing in the MRI scan to explain it. For me, this highlights how important it is to try other research technologies to understand what is happening in the brain in patients with persistent symptoms after Covid-19,” says Ida Blistad, neuroradiologist at the Department of Radiology at Linköping University Hospital and researcher, affiliated with the Department of Health, Medicine and Care at Linköping University and Center for Medical Imaging and Visualization (CMIV).
In their current study, the researchers added a new type of MR imaging called diffusion-enhanced MRI. They were particularly interested in the white matter of the brain. It consists mainly of nerve axons and is very important in transporting signals between different parts of the brain and the rest of the body.
“Diffusion MRI is a very sensitive technology that allows changes in the way nerve axons are organized 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 compared to other imaging technologies that may not pick up,” says Deneb Boito, PhD student in the department of biomedical engineering at the university Linköping.
To get an idea of what diffusion MRI is, we can imagine a large city at night. Car headlights and taillights shine like red and white pearls on the busiest roads. We don’t see the road itself, but we know it’s there because cars can easily drive right there. Similarly, doctors and researchers can gain insight into how the brain is constructed at the microscopic level through diffusion MRI. This technology is based on the fact that everywhere in the brain there is water that moves through the tissue according to the law of least resistance. Water molecules move more easily along nerve pathways. By measuring the movement of water molecules through neural pathways, researchers can indirectly infer the structure of neural pathways, just as we can indirectly know that there is a highway on which many cars are traveling.
Healthcare uses of diffusion MRI include diagnosing stroke and planning brain surgery. In their current study, the researchers used a more advanced version of diffusion MRI. They studied 16 men who had been hospitalized for a severe form of COVID-19 and who were participating in the Linkoping Covid-19 Study (LinCos) at the Department of Rehabilitation Medicine in Linkoping. They still had persistent symptoms after seven months. This group was compared to a group of healthy individuals with no post-Covid symptoms who had not been hospitalized for Covid. The participants’ brains were examined with both conventional MRI and diffusion MRI.
“The two groups differed when it came to the structure of the brain’s white matter. This may be one of the reasons for the neurological problems experienced by the group that suffered from severe Covid-19. This is a result that is consistent with other studies that show changes in the white matter of the brain. However, having studied only a small group of patients, we are cautious about drawing large conclusions. With this technology, we are not measuring the function of the brain, but its microstructure. For me, these findings are a sign that we need to investigate the long-term effects of Covid-19 in the brain using more advanced MRI technology than conventional MRI,” says Ida Blistad.
There are several questions the researchers want to investigate further. It appears, for example, that the white matter in different parts of the brain is affected in different ways, although it is too early to draw conclusions about what these differences mean. An upcoming study will investigate whether the changes detected with diffusion MRI are somehow related to brain activity and how different parts of the brain communicate with each other through the brain’s white matter in patients suffering from post-Covid fatigue.
Another question is what happens with time. An MRI scan provides an image of the brain at that particular moment. Because the participants were only studied once, it is not possible to know whether the differences between the two groups will disappear over time or are permanent.
This story was published by a wire agency feed with no text changes. Only the title has been changed.
