You may know someone who tends to forget things after Covid-19, has a headache, or has not yet fully recovered their sense of smell. These symptoms are included in the phenomenon. blackout where part of the population sank due to the pandemic. If it lasts over time, its effects can be harmful.

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The nervous system suffers

Although SARS-CoV-2 coronavirus infection mainly affects the respiratory system, most patients suffering from covid-19 show neurological symptoms such as loss of smell, headaches, sleep disturbances and memory impairments.

On the other hand, various studies show that patients with neurodegenerative disorders such as Alzheimer’s disease are more likely to suffer from the disease more severely.

Taken together, these signs are a clear indication that the virus has also affected the nervous system. Therefore, it becomes more and more important to investigate what the long-term effects and sequelae of this disease in the brain may be.

Trojan horse and neural pathways

So how does SARS-CoV-2 reach the brain? It is not easy to reach this organ directly because it is surrounded by a true blood vessel wall known as the blood-brain barrier. However, SARS-CoV-2 can circumvent this protection by different mechanisms.

For starters, it can send signals that cause the blood-brain barrier to change. It also has the ability to enter our own cells and use them as a means to infiltrate the brain. The strategy is a real Trojan horse, as it is a pathogen. change costume Something recognizable by our body to overcome obstacles that are otherwise insurmountable.

Finally, SARS-CoV-2 can also travel between neurons scattered throughout our body, forming a neural network. The virus can reach one of the neuronal extensions and pass through them as if it were a highway ending in the brain. Exactly in the nose, the place of entry and infection of the virus is the olfactory nerve, which can be a direct entry route to the brain.

The Covid-19 virus can also indirectly affect the brain. This is what happens when our immune system responds to the presence of foreign microorganisms by releasing molecules called cytokines. These molecules act as a call signal and cause an inflammatory reaction in the tissue where they are found.

This reaction is beneficial in principle because it manages to attract different cells of the army that will fight the infection. However, if it lasts over time, a chronic inflammatory condition develops that can be very dangerous and compromise the functions of different organs, including the brain.

It is precisely in individuals with aging-related diseases that this state of chronic inflammation is common. Specifically, Alzheimer’s patients are known to suffer from neuroinflammation. This means that your brain’s immune system is constantly and over time active, damaging structures and causing further neuron death and neurodegeneration.

Can Covid-19 cause Alzheimer’s?

So what is the link between neurodegenerative processes and covid-19? The relationship between viral infections and neurodegeneration has been known for a long time and it can be deduced that inflammation is the point where both pathologies meet.

In the case of SARS-CoV-2, its ability to induce a general inflammatory state in our body may facilitate the progression of neurodegenerative diseases. In addition, the cytokine storm produced as an intensified defense mechanism has the ability to deregulate physiological parameters. For example, the number of oxidizing molecules increases in neurons due to an imbalance in iron levels that worsens the damage. This leads to more neuron death and more neurodegeneration.

In favor of this theory, some studies show that patients with covid-19 show neuronal losses in the same areas of the brain where damage occurs in Alzheimer’s disease. In addition, neurodegeneration biomarkers are increasing in many patients hospitalized for covid-19.

It is clear that SARS-CoV-2 has a more profound effect on patients’ brains than originally thought. A better understanding of the interaction of this virus with the central nervous system could prevent the development of neurodegenerative diseases such as Alzheimer’s worldwide, without treatment for now.

Juana Andreo López, FPI researcher. Researcher at the Network Biomedical Research Center in Neurodegenerative Diseases (CIBERNED) and the Malaga Biomedical Research Institute (IBIMA), University of Malaga; David Baglietto Vargas, Beatriz Galindo Senior Distinguished Researcher. Researcher at the Network Biomedical Research Center in Neurodegenerative Diseases (CIBERNED) and the Malaga Biomedical Research Institute (IBIMA), University of Malaga and Miriam Bettinetti Luque, a predoctoral researcher at the Network Biomedical Research Center in Neurodegenerative Diseases (CIBERNED) and the Biomedical Research Institute of Malaga (IBIMA). University of Malaga

This article was originally published on The Conversation. Read the original.