There is growing evidence of cognitive impairment in people with COVID-19 infection, causing brain fog and fatigue.

Now, a study published Wednesday in Nature Neuroscience has suggested that the new coronavirus, called SARS-CoV-2, is bad news for the brain because it has been found to cross the blood-brain barrier in mice.

The findings strongly suggest that the virus can enter the brain, affecting cognitive function.

The spike protein, called the S1 protein, dictates in which cells the virus can enter. Lead author William Banks of the University of Washington said the virus does the same thing as its binding protein, adding, “The S1 protein likely causes the brain to release cytokines and inflammatory products.”

The intense inflammation caused by the new coronavirus is called a “cytokine storm.” Upon seeing the virus and its spike protein, the immune system overreacts in an attempt to kill the virus, causing intense inflammation. Eventually, the infected person experience symptoms of brain fog, fatigue, and other cognitive issues.

Banks and his colleagues saw this type of reaction to the HIV virus. They wanted to see if the same was happening with the novel coronavirus.

“We know that when you have the COVID infection you have trouble breathing and that’s because there’s infection in your lung, but an additional explanation is that the virus enters the respiratory centers of the brain and causes problems there as well,” Banks explained. “You do not want to mess with this virus,” he added. “Many of the effects that the COVID virus has could be accentuated or perpetuated or even caused by virus getting in the brain and those effects could last for a very long time.”