New research shows: Having mild Covid-19 can also cause changes in brain structure

According to the New York Times, the new study was published in the journal Nature on March 7. This is the first work to use brain scan data (magnetic resonance imaging) of people with Covid-19 before they contracted the virus and several months after. Therefore, the neurologists not involved in the study highly appreciated this finding.

However, they warn the impact of the changes is not clear and not all F0 can have long-term damage or profound effects on thinking, memory .

F0 mild form is also affected

Research carried out on 785 people 51-81 years old, found shrinkage, tissue damage mainly in brain regions related to smell. The authors at the University of Oxford, UK, say some of the affected areas are also involved in other brain function.

The volunteers are part of the UK Biobank project - a repository of medical data from around half a million people in the UK. Each participant had their brain scanned twice, about three years apart, and performed some basic cognitive tests. Between the two scans, 401 people tested positive for nCoV, all of whom contracted the disease between March 2020 and April 2021. The second scan falls around 4-5 months when they get the virus.

The red-yellow areas are the most atrophied areas of the brain on the 401 F0. (Source: Professor Gwenaëlle Douaud, University of Oxford and the US National Institutes of Health).

The remaining 384 people were in the control group because they had never had Covid-19 and had similar age, sex, medical history, and socioeconomic status as the F0s.

With normal aging, humans lose a small portion of their gray matter each year. According to previous studies, in regions related to memory, people lose 0.2-0.3% of gray matter every year.

But the Covid-19 patients in the study lost more. About 0.2-2% of their gray matter in different brain regions disappeared after 3 years. A 2% reduction equates to about 10 years of aging in the average person. They also lost more overall brain volume, with brain tissue damaged in certain areas.

After 4.5 months of being infected with Covid-19, the thickness of gray matter in the areas of the brain associated with the sense of smell decreased more sharply. This location is also known as the anterior cingulate cortex and the hippocampus (parahippocampal gyrus). This finding is thought to help explain the impaired sense of smell that many Covid-19 patients experience.

In particular, it is remarkable that most of the affected patients are mild F0 patients who do not require hospitalization. Most of the participants treated Covid-19 at home, suggesting that the findings may be relevant to the vast majority of recoveries worldwide.

The study's lead author, Professor Gwenaëlle Douaud, of the Department of Clinical Neuroscience at the University of Oxford, said the number of hospitalized patients in this project was 15, too small to draw conclusions. However, the results still showed that they had more severe brain atrophy than the mild F0 group.

Dr. Serena Spudich, Dean of Global Neuroinfection and Neurology at Yale University School of Medicine, who was not involved in the study, expressed surprise at the amount of gray matter lost in the F0s.

'This is pretty convincing evidence that something changes in the brains of people with Covid-19. However, it is difficult to draw clinical conclusions with F0. We don't want the public to be afraid of having Covid-19 and having brain damage and not being able to function," the expert said.

New research finds that F0 can suffer from brain atrophy, gray matter loss after viral infection. (Photo: WBTW).

Consufused

The second finding that the authors found was that people with Covid-19 had more cognitive decline in tests related to attention, work efficiency, performing complex tasks.

However, other experts say the test is still quite crude and it becomes the limitation of the paper. They agree that it is difficult to assess whether gray matter and tissue damage in Covid-19 patients affects their skills and cognitive abilities.

Assoc. We do not know how this affects the patient's quality of life or function. In general, it is difficult to draw conclusions'.

Meanwhile, Dr Douaud said that although some of the biggest gray matter loss was in areas related to smell, memory and other functions, F0 didn't perform too badly on tests. They take longer to complete the task of connecting data related to letters and numbers. This can indicate weakness in focus, processing speed, and other skills.

According to Dr. Douaud, this impaired capacity correlates with the loss of gray matter in a specific region of the cerebellum. But the authors could not prove cause and effect.

Another significant limitation of the study was that they did not have information on symptoms of F0, including loss of smell. The authors were unable to determine whether F0 experienced sequelae, so it is unclear whether these findings are related to Long Covid status.

The difference between infected and uninfected people increases with age. For example, in the trailfinding test, performance was similar in both 50-60 age groups. But the performance gap was significantly different in the older age group.

"I don't know if this is because young people recover more quickly or they don't suffer as much from the start," Dr Douaud said.

The findings are thought to help explain the cause of post-Covid-19 loss of smell in some F0s. However, this view received mixed opinions. (Photo: Freepik).

This also led Dr Michael to warn that the findings could not be used to explain the situation in young people experiencing brain fog, another cognitive problem after Covid-19. Because gray matter and tissue damage were measured only at one point after infection, they didn't know if it was a transient change followed by recovery or something else.

The cause of the changes in the brain is not clear. The authors mentioned the hypothesis as inflammation, the phenomenon of loss of sensation due to disruption of the sense of smell.

In addition, Dr. Avindra Nath, Head of the Department of Infections of the Nervous System at the National Institute of Neurological Disorders and Stroke, USA, who was not involved in the study, said that we need to pay attention to important questions. other important. That is whether changes in the brain could make F0 more susceptible to dementia.

Meanwhile, other studies did not find similar changes in the brains of people with non-nCoV pneumonia. Dr. Nath recommends that people with other strains of corona virus or the flu should be considered to have more grounds to draw a final conclusion.

Experts say the greatest value of the study is to prove that something is happening inside the brains of people with Covid-19. But it is rather vague and difficult to measure. The task now is to examine the perception, psychiatric symptoms, and behavior of F0 to find out what this finding means for the patient.