Named a dangerous consequence of severe cases of COVID-19

A new study has found that immune responses to severe COVID can cause brain problems. According to the findings, the immune response can cause delirium and fog in the head in patients with coronavirus.

Research shows that severe COVID-19 infections can trigger immune responses that damage nerve cells in the brain, causing memory problems and confusion, and potentially increasing the risk of long-term health problems.

Scientists at King’s College London have found that the immune response to the coronavirus increases neuronal death and has a “profound” effect on regeneration in the brain’s hippocampus, which is critical for learning and memory.

The scientists’ conclusions are still preliminary, but they suggest that COVID can cause neurological problems in patients, while the virus does not need to infect the brain itself. This process is thought to underlie delusions in COVID patients, but may also contribute to brain fog and other issues experienced by people with long-term COVID.

“These neurological symptoms are of great concern to patients and their families, and we hope that our study will help determine which treatment would be most appropriate to reduce or prevent these symptoms,” said study senior author Carmine Pariante, professor of biological psychiatry at the King’s College Institute of Psychiatry. London.

The researchers analyzed the blood of 36 COVID patients admitted to hospitals during the first wave of the pandemic. The scientists found that levels of a protein called IL-6, which immune cells release as a “call to unite” other immune cells, were more than 15 times higher than normal in infected people.

But an even sharper increase in IL-6 levels has been found in COVID patients with delirium, a state of “extreme confusion” that leaves people confused about who they are or where they are. In these patients, IL-6 was six times higher than in other COVID patients. Nearly a third of coronavirus patients admitted to the hospital experience delirium, and in severe cases this rises to two-thirds.

The scientists then investigated how high levels of IL-6 could affect neurons in the hippocampus by exposing lab-grown nerve cells to patients’ blood. They found that the blood of delirium patients increased the normal rate of neuronal death and reduced the formation of new brain cells. It is believed that the damage caused causes delirium.

The harmful effects have been traced back to a cascade of events where IL-6 triggers the release of two related immune proteins called IL-12 and IL-13. Dr. Alessandra Borsini, the first author of the study, claims that the effect of proteins on the creation of new brain cells was “profound”.

However, blocking the proteins protected the brain cells from damage, scientists report in Molecular Psychiatry.

The elderly are particularly vulnerable to delirium after a series of infections and surgeries. The state of confusion leads to a significant increase in the risk of developing dementia.

“We believe that these proteins are responsible for the delusional symptoms in patients with acute COVID-19 and in general in patients with long-term COVID-19 who experience neurological symptoms,” says Dr. Borsini. She added that measuring immune protein levels in patients could help personalize their treatment.

Dr. Thomas Jackson, a geriatrician who studies delirium and inflammation at the University of Birmingham, comments on the results of the study: “They were able to show that increased inflammation has a direct effect on brain cells that we know are associated with delirium and memory problems. Decreased recovery and regeneration mechanisms may begin to explain why people with delirium may have long-term cognitive problems.”

The same immune response may contribute to the “brain fog” reported by some COVID patients, which can persist for months after infection, the expert explains. Confirmation should come from further work, such as the Covid-CNS study, which examines 800 UK patients who had neurological or neuropsychiatric complications due to COVID, he said.