How Does COVID-19 Affect the Brain?

New evidence suggests that the coronavirus is capable of harming other organs other apart from the lungs. Some neurologists have explained how it affects the brain, and we'll tell you about it in this article.
How Does COVID-19 Affect the Brain?

Last update: 08 June, 2020

How does COVID-19 affect the brain?

Currently, knowing this information is one of doctors’ and scientists’ new concerns. There’s already evidence pointing to kidney and heart involvement, too, and so there’s talk of it being a multisystemic disease.

This is a big difference when compared with other viral pathologies such as influenza. These only cause respiratory symptoms, and, at most, a fever.

However, research into coronavirus points to the ACE2 cell receptors as the keys to entry into different cells in the body. The ACE2 receptor, as we’ll explain in this article, is present in many different places in our bodies. This is how COVID-19 affects the brain, by taking advantage of this protein.

It’s important to emphasize that the normal, well-known symptoms remain the same: fever, cough, tiredness, and respiratory distress. However, more and more people are showing secondary signs that can help to catch the infection earlier and gain time. We’ve already mentioned visual problems and loss of smell.

However, we also need to add new research regarding neurological factors.

The ACE2 receptor explains how COVID-19 affects the brain

Coronaviruses have a crown-shaped external form, and that’s where their name comes from. That crown is composed of spicules that have the proteins they need to access human cells. The human receptor is the ACE2 protein.

The receptor exists in the human body to interact in a system called renin-angiotensin. This system of hormones and internal substances is actively involved in the regulation of blood pressure. Therefore, this involves even the kidneys.

COVID-19 affects the brain because we also have ACE2 receptors in some of our neurons. Although there’s no complete confirmation of neurotropism – or the affinity towards neurons by SARS-CoV-2 – there are several well-founded suspicions.

The relevance of the ACE2 receptor is key to understanding coronavirus mortality. Different studies revealed that people with hypertensive disorders are a group with a high incidence of mortality, and this would be explained by the influence of the renin-angiotensin system.

A brain.
The coronavirus could enter the brain through the ACE2 receptor of neurons

Symptoms that reveal how COVID-19 affects the brain

The lack of smell was an early symptom of coronavirus that was pointed out by medical associations around the world. They attribute this to the neurological tropism of SARS-CoV-2. The name given to this is anosmia, and neurologists agree that this would happen due to problems in the neurons belonging to the olfactory system.

Cases of people infected with coronaviruses who have had myositis (muscle inflammation), Guillain-Barré syndrome, and meningitis have also been described. All of these may also have to do with the central and peripheral nervous systems.

An important risk in the effects of COVID-19 on the brain relates to the brain vasculature. In addition to the possible tropism of SARS-CoV-2 in neurons, the inner layers of the brain’s arteries may also have damage.

We know this microscopic endothelial damage as microangiopathy. In the worst-case scenario, this can also lead to intracerebral hemorrhage and a stroke.

Two pathways of coronavirus brain damage

A woman with a mask.
The coronavirus is a systemic disease, as far as we know, and different organs can be affected besides the lungs.

There are two possible pathways that the COVID-19 virus follows to affect the brain. One of these pathways is more direct and is based on the hypothesis of the neuronal tropism of the virus. The other pathway is indirect and is due to the multiple organs that go into shock when the patient is in severe shock in intensive care units.

The direct route hasn’t been completely proven, as we’ve already said. SARS-CoV-2 would enter the neurons via the ACE2 receptor in the same way as it enters the lungs and kidneys.

On the other hand, the indirect route is the one that affects the evolution of the coronavirus within the body. Firstly, we have the respiratory issues, then pneumonia, failure of multiple organs, decreased blood flow to the brain and, consequently, the death of neurons that don’t receive sufficient oxygen.

Does COVID-19 affect the brain?

Overall, we now know that COVID-19 affects the brain, either directly or indirectly. Meanwhile, scientific research will continue to keep us informed, and also reveal new aspects of this pandemic.

This knowledge is vital for health care workers in intensive care units who can tailor their therapy based on the findings. Such valuable information improves patient survival, adding hope amidst the uncertainty of the global coronavirus outbreak.

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  • Hoffmann, Markus, et al. “The novel coronavirus 2019 (2019-nCoV) uses the SARS-coronavirus receptor ACE2 and the cellular protease TMPRSS2 for entry into target cells.” BioRxiv (2020).
  • Bonow, Robert O., et al. “Association of coronavirus disease 2019 (covid-19) with myocardial injury and mortality.” JAMA cardiology (2020).
  • Sedaghat, Zahra, and Narges Karimi. “Guillain Barre syndrome associated with COVID-19 infection: a case report.” Journal of Clinical Neuroscience (2020).
  • Castellón, Roberto León, Juan Enrique Bender del Busto, and Luis C. Velázquez Pérez. “Afectación del sistema nervioso por la COVID-19.” Anales de la Academia de Ciencias de Cuba 10.2 (2020).