It is no longer a secret that COVID-19 has a certain impact on the brain, something that has already generated research done in several places around the world. This week, a new study from Yale University, USA, provided the first clear evidence that, in some people, the coronavirus can invade brain cells, sucking up all the nearby oxygen and killing neighboring cells.
It is unclear how the virus reaches the brain, but experts call attention to the possibility that brain infection is rare. Some people, however, are susceptible due to their genetic background, a high viral load or other reasons still under investigation. “If the brain gets infected, it can have a lethal consequence,” says Akiko Iwasaki, an immunologist at Yale University who led the work, in an interview with The New York Times.
The scientists analyzed patients’ brain images and symptoms. “We had not seen much evidence that the virus can infect the brain, although we knew it was a potential possibility. These data only provide a little more evidence,” says Dr. Michael Zandi, consultant neurologist at the National Hospital of Neurology and Neurosurgery of Great Britain.
Other pathogens are known to infect brain cells. Immune cells flood the damaged sites, trying to clear the brain, destroying the infected cells. The coronavirus is much more stealthy: it exploits the mechanism of brain cells to multiply, but it does not destroy them. Instead, it chokes oxygen to adjacent cells, causing them to wither and die. The researchers found no evidence of an immune response to remedy this problem. “It is a kind of silent infection. This virus has many evasion mechanisms “, says the expert.
The coronavirus appears to rapidly decrease the number of synapses, the connections between neurons. In addition, the study also points out that the virus infects a cell through a protein on its surface called ACE2. This protein appears throughout the body and especially in the lungs, explaining why they are favorite targets of the virus. The team examined two sets of mice – one with the ACE2 receptor only in the brain and the other with the receptor only in the lungs. When the researchers introduced the virus to these animals, those infected in the brain lost weight quickly and died within six days. The infected mice in the lung, on the other hand, showed no changes.
Researchers will need to analyze many autopsy samples to estimate how common brain infection is. Some cognitive symptoms, such as brain fog and delirium, may be more difficult to detect in sedated patients. Doctors should plan to reduce sedatives once a day, if possible, to assess patients with COVID-19 to increase knowledge about this issue.
Source: The New York Times