Can the coronavirus invade the central nervous system?

COVID-19 is generally known as a type of respiratory disease, but there is growing evidence suggesting that the infection can severely affect other organs, including the brain. Ádám Dénes and his colleagues were among the first researchers in the world to examine the brains of people whose death is related to the coronavirus infection. Their results might lead to the development of treatment methods that are different from previous ones.

Severe pneumonia, artificial respiration, chronic illness, high rate of mortality among elderly people − these are the major keywords appearing in the news every day in connection with the outcome of coronavirus-related diseases. The virus was named SARS-CoV-2, and the first half of the acronym comes from the abbreviation of the severe acute respiratory syndrome. As the name suggests, the primary symptoms affect the respiratory tract and the lungs.

However, as more and more clinical data is available on the disease, growing evidence suggests that both the nervous system and the brain may be involved in the infection, and research in this area might be crucial in the most severe cases. Ádám Dénes, a researcher at the Institute of Experimental Medicine (abbreviated KOKI in Hungarian), and his colleagues, including neuropathologist Tibor Hortobágyi, wanted to map the possible neurological effects of the current coronavirus infection, MTA reported.

Emergency mode

When we have an infection, our immune system reacts specifically to pathogens and foreign substances, such as the cell wall of bacteria and the genetic material or the protein shell (capsid) of viruses. The entry of these pathogens causes inflammatory reactions in the human body. In response to this reaction, our liver starts to produce acute-phase reactants that prepare our body for defence. By switching to “emergency mode,” the body is forced to retune many of its systems that function properly in a normal situation. Similar processes occur in the case of other diseases; for example, certain chronic diseases, such as high blood pressure (hypertension) or diabetes, already keep the body’s inflammatory system under constant stress.

It is possible that the coronavirus enters the brain

Inflammatory changes in the body are also perceived by our nervous system, and through the reaction of some of our brain centres, especially the hypothalamus, the well-known symptoms of malaise, loss of appetite, fever, and other common symptoms start to develop. However, the impact of viral infections can go even further.

The overproduction of inflammatory factors can also trigger processes that can affect brain centre circulation and the respiratory centre. This phenomenon might stand behind the clinical observations in which the respiration of some COVID-19-infected patients collapsed in a way that would not otherwise be justified by the condition of their lungs.

Similar processes caused by systemic inflammation − including circulatory collapse, cardiac arrest, liver, kidney, or other organ dysfunction, and various neurological symptoms − can be observed in septic conditions caused by bacteria or viruses.