Researchers Find COVID can Cause Disruption in the Brain
Stanford researchers recently published a study which examines the brains of those who died from COVID-19, finding they resembled those with Alzheimer’s disease and other degenerative conditions.
“We want to understand how the brain responds to this virus and people with severe disease, and it was a pretty big challenge because no one was sure how bad this virus is, and there was no protocol for how to recover brains from people who died from this disease,” said Tony Wyss-Coray, the senior author of the study and D.H. Chen professor in Neurology and Neurological Sciences at Stanford University.
To conduct the study, Wyss-Coray and his team profiled over 65,000 brain tissue samples from the brains of eight older patients who had died from COVID-19, and 14 patients who had died from other causes, including influenza.
They used a new technology which has revolutionized neurological research and which uses RNA sequencing in an unbiased way, examining different cell types in the brain tissue and their composition.
“The challenge was to get any tissue from patients, and we had to take whatever we could get. We would ideally have used tissue of those who were still alive and had survived. This is one of the biggest challenges in studying the brain,” said Wyss-Coray.
One of the other challenges, Wyss-Coray said, is knowing where to look for the presence of the COVID-19 virus, as the brain is huge and the amount of tissue that a researcher can observe with the available techniques is about the size of a pinhead.
“It’s possible the virus is in places we have not looked at, or that the virus that was in the brain left again, but our studies did not detect any trace of the virus itself,” said Wyss-Coray.
However, what they did find was a greater presence of T cells in those who died from COVID-19 than those who did not. T cells provide immunity to foreign substances by circulating in the body and locating a specific antigen to attack. This slight uptake of T cells has also been previously observed in the brains of those who had Alzheimer’s and Parkinson’s disease.
One explanation, Wyss-Coray said, is that COVID-19 infection might cause inflammation in the brain to sound an alarm signaling the recruitment of T cells. Even after an individual has recovered from the virus, the inflammation does not stop, causing confusion within the immune system.
“You recruit cells even though there is nothing to treat. We call this autoimmune response destruction of your own cells fighting your own cells, even though nothing is wrong,” said Wyss-Coray.
“These factors can cause acute disruption of brain circuits and that disrupts the normal transmission of neural cells, it’s almost like you have a static on the TV,” he continued.
This signaling imbalance might help explain why those with lingering symptoms of COVID-19, known as long COVID, experience brain fog symptoms, like fuzzy thinking, forgetfulness, difficulty concentrating, and depression.
Wyss-Coray said understanding the effect of the inflammation on the brain may also help in understanding why cancer survivors and those who have gone through chemo also frequently report experiencing brain fog.
“We conclude the virus does not have to get into the brain to cause these molecular changes we observed, but how much disruption do you need to have functional impairments? We are still trying to figure that out,” said Wyss-Coray.
To better understand the mysteries of the brain, Wyss-Coray is hoping to collect samples of liquid cerebral spinal fluid from people who survived COVID-19 and get additional information as to whether they have lingering symptoms or not, and how these findings about inflammation differ from people who didn’t have the virus.
This research could involve conducting a longitudinal research study that follows volunteers over time who donate the spinal fluid, however this procedure is extremely invasive as it involves puncturing the spine and pulling out the fluids.
“Relatively speaking, this is a young disease, and it will take time to figure it out, but what we can say is the brain looks messed up in those who died,” said Wyss-Coray.