Shortly after the first wave of COVID-19 infections, doctors around the world began to notice something strange: a series of persistent effects in patients, long after they appeared to have recovered from the virus.
These unusual neurological symptoms (which include fatigue, memory loss, confusion, and other abnormalities) are sometimes known as “brain fog” or “brain COVID,” and new research may have identified an underlying cause of the disease.
“We were initially approached by our critical care medical colleagues who had observed severe delirium in many hospitalized patients with COVID-19,” says neuro-oncologist Jessica Wilcox of the Memorial Sloan Kettering Cancer Center (MSK) in New York City. .
“That meeting became a huge collaboration between neurology, critical care, microbiology and neuroradiology to learn what was going on and see how we could better help our patients.”
As part of the new study, Wilcox and other researchers examined the cerebrospinal fluid of 18 cancer patients suffering from neurological dysfunction (also known as encephalopathy) after being infected with the SARS-CoV-2 virus.
Initially, it was suspected that an ongoing viral infection could be the cause of the symptoms of brain fog, but microbiological analysis of the fluid taken from the spinal taps did not reveal any signs of the virus, suggesting that patients had recovered from COVID-19
Still, the search gave an important clue as to what was going on.
“We found that these patients had persistent inflammation and high levels of cytokines in the cerebrospinal fluid, which explained the symptoms they had,” explains MSK researcher and co-author of the study, Jan Remsik.
Cytokines are a broad category of proteins involved in signaling the immune system.
In some cases of coronavirus, an overproduction of these molecules causes what is known as a cytokine storm, which can cause excessive inflammation and is potentially fatal.
A similar phenomenon showing elevated levels of inflammatory cytokines is sometimes seen as a side effect of chimeric antibody receptor (CAR) T cell therapy, an immunotherapy treatment, which can also cause confusion, delirium, and other neurological effects that have a resemblance to the COVID brain. fog.
The thought is that flooding of these inflammatory chemicals from the immune system drains into the brain and produces symptoms of encephalopathy as seen in patients.
Although this is the largest study to date to demonstrate this potential link between COVID-19 and post-infection neurological effects, we will need much more data to unravel this association.
That said, the findings here suggest that anti-inflammatory drugs may be helpful in mitigating brain fog in patients and may highlight new directions in the diagnosis of this strange persistent discomfort.
“We used to think that the nervous system was a privileged organ for immunity, that is, it had nothing to do with the immune system,” explains MSK neuro-oncologist Adrienne Boire.
“But the more we look, the more we find connections between the two.”
The findings are reported in Cancer cell.