Coronavirus can damage the brain

How can the coronavirus reach the brain?

The brain!  An area in the body that supposed to be highly protected!

More and more research continues to reveal the dramatic effect that COVID-19 exerts on the central nervous system. Around 36% of COVID-19 patients show neurological symptoms. This open a new question not only for the  COVID-19 treatment, but also it's a long term effects. The empact COVID-19 has on the brain is often overlooked due to the complicated diagnostics of medically unstable patients. How ever in the case of brain infection, the coronavirus can lead to a number of neurologic symptoms like headache, seizures, loss of control over body movement and lot of vital senses such as test and smell. Our brains are protected against viral and bacterial infections thanks to the Blood-Brain-Barrier which a thick natural border that separates the brain from the rest of the body. The border is made of cells that only let very small particles to pass through. However severe inflammations the comes with diseases like COVID-19 can destroy this barrier.  Some viruses can even use inflammatory cells as 

"Trojan horses" to trick their way into the brain. The new coronavirus, SARS-CoV-2, is throught to be one of them.

Another possibility is that the cells that build the Blood-Brain-Barrier themselves get infected and then allow the virus to pass through this border into the brain. 

Brains of infected COVID-19 people show the Presence of the virus in endothelial and neuronal cells.

The virus, however, can use another way to travel to the central nervous system. One such way is accomplished through the axons threadlike parts of the neuron that are found all over body. Through these axons, the virus can potentially travel to the main part of neurons in the brain or spinal cord. 

Brain cells that are damaged release chemical called biomarkers that can be found in the cerebrospinal fluid which is a colourless body fluid found in the brain and spinal cord. The presence of these biomarkers in the blood of COVID-19 patients, especially patient with severe cases, indicates that brain cells have been attached and damaged by the coronavirus.

Even the host's immune system can misdirect it's attack when faced with a viral infection in the brain and damage the central nervous system. 

The brain is fragile organ with most of its cells lacking the ability to regenerate. This mean that the damage to the brain can be lasting and potentially lead to Neurological disorder.

In a recently published study researchers used a brain model called BRAIN SPHERE  

 made from specific stem cells to test whether SARS-CoV-2 can infect neurons. Three days after the infection, viral particles were found in the body of some brain cells indicating that infection has indeed occurred. 

The coronavirus targets neurons because they have a specific receptor called ACE2. Which SARS-CoV-2 can recognise and used as the key to enter into the brain cells. This is the same receptor that the virus utilizes to enter into other cells like lung cells, heart cells, kidney cells and the insulin producing cells in the pancrease. Among other respiratory virus that can invade the brain is Influenza (a flu virus). Other coronaviruses have also previously shown to infect the brain in the both animals and humans.

Previously thought to be rare, viral infection of the brain can lead to brain inflammatio, meningitis and lasting neurological damage. These findings direct the attention to the current treatment of COVID-19 patients the largely overlook neurological symptoms. Between the challenge of identifying wether the brain has been infected, unstable patients, and the lack of direct treatment, diagnosing the brain infection in a timely manner could help us tackle such symptoms as early as possible.