COVID-19 and Your Brain: What You Should Know

Medically Reviewed by Melinda Ratini, MS, DO on May 19, 2023
4 min read

About 1 in 7 people who’ve had the COVID-19 virus have developed neurological side effects or symptoms that affected their brain function. While the virus doesn’t directly attack your brain tissue or nerves, it can cause problems that range from temporary confusion to strokes and seizures in severe situations.

This trend is like other “brain fog” complications seen in previous viruses, such as SARS and H1N1. It may take months for experts to discover the reasons behind these issues. But they suspect it has largely to do with the stress of living through a pandemic paired with the physical toll that the COVID-19 virus takes on the body.

COVID-19-related “brain fog” is a vague term that describes the many lingering symptoms of the virus that relate to mental function. These side effects usually happen weeks after someone has healed from the initial flu-like COVID-19 symptoms. Up to 20% of people who’ve had COVID-19 developed short-term memory loss, poor attention span, or fatigue.

Other people reported more serious brain-related effects from COVID-19. Some experts believe this is the result of having a more severe illness or suffering from low oxygen for a prolonged periods of time. These can include:

Others who’ve had COVID-19 are developing problems with nerves outside the brain and spinal cord. These include Guillain-Barré syndrome (GBS), which can cause lung failure or paralysis. The exact number of people that get this condition is unknown, but it seems to be rare.

Experts also say that the rise in GBS cases may not have to do with COVID-19 at all. Instead, someone might’ve caught it when they had COVID-19, but it wasn’t actually tied to the virus. Researchers are still studying the tie between GBS and COVID-19.

Being sick enough to require home oxygen therapy might also lessen the volume of gray matter in the outer layers of the brain. A study found that people who went on oxygen therapy for the virus had lower gray matter volume in their brain’s frontal lobe when compared to those with COVID-19 who didn’t need oxygen treatment. Experts have linked lower gray matter in this area of the brain to more intense disability for up to 6 months after COVID-19 recovery.  <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Learn more about how disability for post-COVID syndrome works.

Similarly, those who had fever with COVID-19 had lower gray matter volume in other parts of their brain (their temporal lobe) than those who didn’t have fevers with the virus.

But these studies were very small. Researchers need to study the trend more to confirm any results.

Experts don’t know exactly why our brains are affected by COVID-19, but they have many theories:

Severe infection. One reason that COVID-19 may affect the function of your brain is due to the fact that the virus is able to enter the central nervous system (brain and spinal cord) and cause sudden infection. Researchers have found the virus’s genetic material in the spinal fluid of some cases within China and Japan. Similarly, a case in Florida showed viral particles in brain cells.

This might happen from the virus entering one’s bloodstream or nerve endings. Doctors believe that this could be related to why some people lose their sense of smell with COVID-19. They think that this could happen if the virus enters through the olfactory bulb, which is the area of your brain near the sinuses of your nose that communicates information about smell to your brain.

In one study that involved people who died from COVID-19, experts found that there was damage and leakage from blood vessels into the olfactory bulb. But researchers found no evidence that the virus actually entered the brain.

Immune system overdrive. Another reason may be that your immune system gets overwhelmed as it fights off COVID-19. This could create an inflammatory response that could lead to harm to your tissues and organs. This response alone can end up causing more damage to your body than the virus itself.

Changes in your body. Another theory is that the physical changes in your body from COVID-19 -- such as high fevers, low oxygen levels, or organ failures -- lead to or heighten the risk for brain complications. This could lead to delirium or even coma in severe COVID-19 cases.

Blood clotting. The last suggestion for why the virus may affect your brain has to do with the fact that people with COVID-19 are at a higher risk of having a stroke. Your chances of having blood clots with the virus are higher. These clots can form in veins deep inside your body or inside of your lungs. But if they block or narrow the arteries that lead to your brain, you could have a stroke.

If you notice any neurological changes after having COVID-19, it’s best to contact your doctor right away. They can help you treat symptoms and feel better as soon as possible.

Doctors are still studying the ties between COVID-19 and your brain. In addition to getting proper care, it’s important to report any issues you have after the virus. This will help experts learn how best to treat these cases in the future.