Covid affects the brain and can cause changes even in light...

The study, coordinated by researchers from the State University of Campinas (Unicamp), had the participation of the University of São Paulo (USP), the Federal University of Rio de Janeiro (UFRJ) and the National Biosciences Laboratory (LNBio). The article with the results was published in a pre-print version on the medRxiv platform and is still being evaluated by an international scientific journal.

The results reveal that:

• the virus promotes significant changes in the structure of the cortex, the brain region richest in neurons and responsible for complex functions such as memory, attention, awareness and language.
• the virus infects and replicates in astrocytes, which are the most abundant cells in the central nervous system and are star-shaped.
• atrophies were observed in areas related, for example, to anxiety, one of the most frequent symptoms in the studied group.

“We met many patients who, even though they were cured of Covid-19 about 2 months ago, continued to have neurological symptoms, such as severe headaches, excessive sleepiness, altered memory, in addition to loss of smell and taste. In some rare cases, even seizures, and these patients had never felt it before “- Clarissa Lin Yasuda, researcher at Unicamp

According to the researchers, two major discoveries were made regarding the mechanism of action of the virus. When SARS-CoV-2 enters the brain, it attacks a kind of support cell responsible for metabolic processes, hindering the production of energy and nutrition of neurons and, consequently, can lead to the death of brain tissue.

Some studies had already demonstrated the presence of the new coronavirus in the brain, but this time the experiments proved that the infection and replication in the astrocytes.

The presence of the virus was confirmed in the 26 samples studied, collected by means of a minimally invasive autopsy performed on patients who died because of Covid-19.

In addition, the study provides further evidence that the access route to the brain is the nose. In another arm of the research, the analysis of MRI images in mild patients who had not yet needed hospitalization demonstrated an important reduction in the cerebral cortex in some regions close to the airways, called the orbitofrontal region, proving that these are changes in the brain structure.

Some areas had less thickness than the average observed in brains not affected by Covid-19, while others presented an increase in size which, according to the authors, could indicate some degree of edema. It was also in this region that atrophies were observed.

Unicamp researcher Clarissa Lin Yasuda also states that there is a suspicion that the virus may activate genetic diseases such as schizophrenia, Parkinson’s and Alzheimer’s. “What we still do not know is the severity of these injuries, whether they are transient or if they can be irreversible, so we are going to monitor these patients for the next 3 years to see if the virus triggers degenerative diseases in those who have some genetic potential,” explains researcher.

Until now, scientists were unsure whether the virus was actually inside brain cells or whether the symptoms were caused by other problems brought on by the disease, but studies have shown the virus to act on brain cells. Although most patients with Covid-19 have pulmonary symptoms, such as pneumonia and shortness of breath, about 30% of those infected end up with neurological or psychiatric symptoms.

“In critically ill patients, the death of neurons was already expected because they have low blood oxygenation and this damages the brain a lot, but a mild or moderate person having a significant change like this is much more worrisome”, emphasizes Daniel Martins-de- Souza, a researcher at Unicamp and the D’Or Institute for Research and Education (IDOR), one of the study leaders.

The discovery is important because it can change the type of treatment that patients are receiving. One of the questions that needs to be answered is how the virus reaches the central nervous system and what is the mechanism of action to enter astrocytes.

“Until now, we considered that some symptoms were secondary to the disease, but we are seeing that, in some people, neurological and psychiatric symptoms can be primary, that is, there is no point in treating this patient’s lung because the coronavirus is in brain. Understanding that the virus changes the way we make energy in cells, we were able to start thinking about how to use the right drugs ”, explains Martins-de-Souza.

For Lin Yasuda, the main contribution is to help find targets for treatment. “If I know that Sars-CoV-2 interferes with astrocytes, I can invent a drug that does not let it enter this cell, or that strengthens that cell, or I can, perhaps, create a medication that can be used via to help prevent the new coronavirus from entering the body. This increases our chances of fighting the disease. When I don’t know who I’m going to fight with, how will I defend myself? ”, Highlights the neurologist.