One of the lingering side effects of COVID-19 is a neurological symptom known as brain fog. It includes decreased memory and attention span, and has affected more than 30 percent of participants who have recovered from COVID-19, according to research in Infection.*

The research indicates that brain fog isn’t limited to hospitalized patients; it also impacts people who have had a mild case of COVID-19.

To understand why this may be the case, two neurologists, Dr. Mitchell Elkind, an attending neurologist on the stroke service at New York-Presbyterian/Columbia University Irving Medical Center, and Dr. Alexander Merkler, an assistant attending neurologist at New York-Presbyterian/Weill Cornell Medical Center, shared their insights. 

What Is COVID-19 brain fog?

Dr. Merkler: After patients recover from the main symptoms of COVID-19, like shortness of breath, cough, and fever, many are reporting they feel brain fog on a long-term basis. This often includes loss of memory, trouble “finding” words, problems with attention and concentration, and being overwhelmed by simple tasks. This cognitive dysfunction occurs in patients of all types, not solely in patients who have had stroke or infection of the brain or seizures during diagnosis.

What causes this? 

Dr. Elkind: In some patients, a stroke can occur during COVID-19 diagnosis, and cognitive disturbances would result. But some are having a mild illness, recovering, and then dealing with a persistent brain fog. This could be a result of the activation of the immune system, which releases molecules to fight off infection and often has an impact on the nervous system.

Is this particular immune response unique to the coronavirus?

Dr. Merkler: This is not unique to the coronavirus; immune system activation occurs when fighting off a gamut of illnesses. The body creates an inflammatory response to kill the virus; in some cases, our bodies can overreact to this response and attack our healthy cells.

Dr. Elkind: This has also been seen in streptococcal pneumonia; the immune response against the strep infection attacks the brain, sometimes leading to the development of movement disorders and other psychiatric syndromes. So this is not considered specific to COVID; currently, we’re seeing a lot of COVID cases and so these aftereffects are being seen all at once more so than with other viruses or infections.

What signs/symptoms should someone look out for, and at what point may they want to see a doctor?

Dr. Elkind: If your symptoms are interfering with your everyday life, then you will want to see a doctor. Additionally, if brain fog comes with other symptoms such as weakness, difficulty speaking, loss of vision, numbness and tingling, which doctors refer to as focal symptoms, your doctor will want to check any potential damage to your nervous system.

Dr: Merkler: As mentioned before, coronavirus can lead to stroke, so it’s vital that you see your doctor, get scanned, and get brain imaging and blood work, so they can rule out brain injury.

Will a brain scan show neurological symptoms developed post-COVID diagnosis?

Dr. Elkind: Magnetic resonance imaging, or MRI, is sensitive, but it might not show signs of brain damage. If the virus is affecting the brain at a microscopic level, it may be difficult to visualize it on current imaging modalities like MRI.

However, there are several reasons why the nervous system may malfunction besides permanent injury, such as inflammation leading to an overactive immune mechanism and tackling healthy cells as mentioned above or COVID-19 antibodies interacting with nerve cells.

How do you treat brain fog?

Dr. Elkind: Brain fog is being treated similar to treatment for a head injury. Sleep is essential and avoiding risky behaviors, like smoking, is important.

Dr. Merkler: Evidence shows that mental fog is not permanent, so most people will get back to normal at some point. It is important to be optimistic about your recovery and slowly get back to their normal routine. Eating healthy, engaging in physical activity, and keeping your mind busy, such as work or puzzles, are all helpful.

*Fishman, L. (2021, February 3). Can COVID-19 Cause Brain Fog? NewYork-Presbyterian. https://healthmatters.nyp.org/what-is-causing-covid-brain-fog/

Much about the novel coronavirus, i.e., COVID-19, is still not fully understood. As research progresses and our knowledge of the virus increases, information can change rapidly. We strive to update all of our articles as quickly as possible, but there may occasionally be some lag between scientific developments and our revisions.