How Does COVID-19 Affect the Brain?

The symptoms of COVID-19 are wide ranging. Most people who contract the virus will experience an array of conditions, including respiratory issues, weakness, nausea, and fever, according to the Centers for Disease Control and Prevention (CDC). As the disease and its variants have ravaged the globe, the list of symptoms has grown too, with evidence of compromised cognitive impairment becoming apparent.

A May 2022 study published in EClinicalMedicine found that patients who experienced severe COVID-19 illness had significant cognitive deficits after recuperating. The 46 participants were also tested for anxiety, depression, and PTSD.

"COVID-19 has been associated with multiple neurologic symptoms such as headache, dizziness, myalgia, confusion, alteration of the sense of taste and smell, weakness, strokes, and seizures," said William C. Davison MD, FAAN, neurologist at Chicago-area Northwestern Medicine Lake Forest Hospital. Additionally, an April 2022 review of neurological components related to COVID-19 infection in the Journal of Chemical Neuroanatomy reported neurological-based illnesses such as encephalitis, neuromuscular disorders, and meningitis in patients. Also, some may develop delirium, a state of confusion, at the onset or later in the hospital, according to the National Institute of Neurological Disorders and Stroke (NINDS).

Further, the disease has been associated with acute disseminated encephalomyelitis (ADEM), a condition that causes widespread inflammation in the brain and spinal cord, which comprise the central nervous system. This rare, potentially fatal condition attacks the myelin, the protective covering of nerve fibers in the central nervous system, according to the NINDS. If this protective covering is absent or inadequate, nerves are unable to effectively transmit information. The symptoms that may result from ADEM range from headache and fatigue to visual loss and paralysis.

Can These Conditions Affect Brain Functioning?

Researchers in the United Kingdom conducted a study, published in March 2022 in Nature, with the intent of finding connections between COVID-19 and changes to the brain. They looked at the brain scans of 785 individuals—401 of whom had experienced milder infections of the disease. The researchers found that, compared to the individuals in the control group, those who had contracted COVID-19 showed more evidence of cognitive decline between the first and the second scan—indicating a link between COVID-19 and brain functioning.

Research has also suggested that COVID-19 could cause further brain damage through brain inflammation and nerve damage. A March 2021 article published in JAMA Psychiatry notes, "SARS-CoV-2 can damage endothelial cells"—cells that guard the brain against pathogens or toxins as part of the blood-brain barrier. When these cells are compromised, both brain inflammation and brain damage may occur.

Also, acute COVID-19 infection can lead to complications concerning blood, such as brain bleeding, weak blood vessels, and blood clots, which may cause strokes, according to NINDS. While rare in COVID-19 patients, strokes can cause brain damage independent of infection from the disease. An April 2021 study from JAMA Network Open showed that individuals with COVID-19 were more at risk of experiencing acute ischemic strokes, in which a sudden loss of blood to the brain causes a failure in neurologic function.

Earlier in the pandemic, patients who didn't display severe respiratory symptoms, such as breathing difficulties, may not have been tested for neurological complications in time to avoid damage. "Some patients go from no symptoms and a normal outcome to multiple organ failure and even death," said Dr. Davison.

Experts are continuing to learn what's causing the presentation of neurological complications in COVID-19 patients. The symptoms may present themselves as a result of the systemic impact of the illness, as COVID-19 doesn't seem to directly attack the brain, according to NINDS. "Sometimes these symptoms can be the result of systemic disease such as acute respiratory distress syndrome (ARDS) but other times may be related to either direct involvement of the virus to the nervous system or an abnormal immune response to the virus," added Dr. Davison.

Can Neurological Effects of COVID-19 Be Avoided?

To lessen the risk of experiencing neurological symptoms due to COVID-19, the CDC has provided ways to protect yourself against infection in the first place, such as monitoring your health on a daily basis, practicing physical distancing, and wearing a mask. As of April 2022, the CDC has also recommended getting a COVID-19 vaccine and staying up to date with boosters. Finally, if you or someone you know is infected and starts to experience confusion or an inability to stay alert, seek immediate medical attention.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up to date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.