Covid-19: a study reveals how the virus invades the brain

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It is no longer a secret: Covid-19 can be the cause of neurological damage and heart damage. A new study reveals how the coronavirus can invade the brain with deadly consequences.

We know it: the symptoms of Covid-19 are fever, cough or fatigue. Signs that may get worse after a few days with the onset of breathing difficulties. This worsening of the disease is believed to be due, in some of these patients, to a mysterious phenomenon called a "cytokine storm." It is characterized by an overproduction of molecules called cytokines, which trigger a violent inflammatory response in the immune system that can cause damage to organs such as the lungs or liver, as explained by the New York Times.

These two organs are not the only ones that can be affected in the event of Covid-19: Research suggests that the coronavirus could also attack the heart and brain. A new study even reveals that Covid-19 could invade the brain.

Covid-19 and the brain: deadly consequences

To carry out this work, carried out by researchers from Yale University (United States) and published on the scientific pre-publication site BioRXiv, the researchers started from the following observation: almost half of the patients affected by Covid -19 reported symptoms neurological, including headache, confusion, and delirium.

To understand how this disease attacks the brain, they analyzed the brain tissue of a person who died of Covid-19, conducted an experiment on mice, as well as organoids, mini-organs grown in the laboratory.

They discovered that the coronavirus entered cells through a protein on their surface, called ACE2, before usurping cellular components to speed up viral reproduction and deprive other cells of oxygen. During their experiments with mice, one with the ACE2 receptor expressed only in the brain and the other with the receptor only in the lungs, they found that the brain-infected mice lost weight rapidly and died within six days. This was not the case for those infected through the lungs.

Results suggesting that coronavirus infections that affect the brain of patients may have more serious consequences than those that affect the respiratory tract. "If the brain is infected, it could have a fatal consequence," concluded Akiko Iwasaki, an immunologist and lead author of the study.

Coronavirus: more and more neurological damage

Another study conducted last February by Chinese and Japanese researchers and published in the Journal of Medical Virology already indicated that several patients with Covid-19 presented, in addition to respiratory distress, neurological signs such as headaches, nausea and vomiting. "Mounting evidence shows that coronavirus is not always confined to the respiratory tract and that it can also invade the central nervous system inducing neurological diseases," the researchers write.

Cases of patients with Covid-19 and showing neurological signs have also been reported, as indicated by doctors from the Henry Ford Health System in Detroit (United States) who had presented, in the journal Radiology, a case of acute necrotizing hemorrhagic encephalopathy in a patient affected by the coronavirus. Neurologists from the Renmin Hospital of Wuhan University (China) have identified a case of acute myelitis after coronavirus infection, which they presented in the scientific journal prior to publication medRxiv.

In Brescia, Italy, a unit dedicated to patients with Covid-19 and affected by neurological damage had even been opened. And for good reason: "there is a dramatic increase in the number of ischemic strokes and thromboses, probably due to the virus," explains neurologist Alessandro Pezzini to Neurology Today.

Covid-19: the cause of heart damage?

Another study, published in the journal JAMA Cardiology, found that heart damage was common in Covid-19 patients and was associated with an increased risk of death.

Proof of this is that of the 416 patients followed for the purposes of this study, 19.7% had been affected by a cardiac injury during their hospitalization. 51% of people with heart damage had died, compared with 4.5% of those who did not.

However, the mechanisms that operate in this phenomenon are not yet clear. "It is extremely important to answer the question: Is your heart affected by the virus and can we do something about it? Ultimately, it could save many lives," New York cardiologist Dr. Ulrich Jorde told Scientific American.

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