Researchers may have answer to why COVID patients develop 'brain fog'

PALO ALTO, Calif. -- Researchers at Stanford Medicine have discovered a possible link to the "brain fog" that some COVID-19 patients have experienced.

Working with a team in Germany, they found that the virus triggers brain inflammation, which leads to symptoms similar to Alzheimer's and Parkinson's.

It's well known the stress the COVID-19 virus puts on the respiratory system. Now, researchers have discovered how the virus appears to be inflaming the brains of patients who die from COVID.

Researchers at Stanford Medicine collaborated with counterparts at Germany's Saarland University. An analysis of brain tissue from eight patients showed inflammation that creates brain fog or cognitive decline, similar to symptoms of Alzheimer's and Parkinson's.

"I think it will be interesting and important to figure out whether this inflammation could actually be targeted or treated and where the inflammatory, anti-inflammatory treatments could help alleviate some of these symptoms," said Prof. Tony Wyss-Coray PhD, whose lab had 20 researchers engaged in the project.

Inflammation showed up as brown markers in their analysis. That triggered the body's immune system to respond by sending in a surge of T-cells to fight the virus.

The brain tissue showed no presence of the COVID-19 virus, which Stanford researchers cannot fully explain yet. Did the T-cells destroy infected cells or respond only to find no virus present?

The preliminary findings were published this week in Nature.

However, more research needs to be done to see if a treatment can be developed for the brain inflammation. That could be significant for patients who experience long-term memory loss or confusion even as they survive and recover from COVID.

"I think we can tone down the inflammatory response overall," said Dr. Wyss-Coray. "I think there are tools to do that."

The research began a year ago when it was difficult to obtain brain tissue. More knowledge will result as more samples can be analyzed, especially from countries where COVID cases and fatalities remain high.