A study shows that “brain fog”, long associated with Covid, can be caused by leakage of the blood-brain barrier, which controls the substances and materials that enter and leave the brain.
What is the cause of the phenomenon called “brain fog”, associated with Long Covid – Photo Archive
Specifically, if the barrier that controls substances entering and leaving the brain is out of balance, it can cause changes in neural function, the researchers say.
Many people suffering from Long Covid experience difficulty concentrating, forgetfulness, a symptom that can be caused by the leakage of the blood-brain barrier, according to recent research, cited by The Guardian.
“It is about regulating the balance between substances in the blood and the brain. If it is dysregulated, then it can lead to changes in neural function, and if the phenomenon happens in the regions of the brain that allow memory consolidation/storage, then it can wreak havoc.“said Professor Matthew Campbell, co-author of the research from Trinity College Dublin.
The study was published in the journal Nature Neuroscience. The scientists analyzed serum and plasma samples from 76 patients who were hospitalized with Covid in March or April 2020, as well as from 25 people before the pandemic.
A protein from the brain found its way into the blood
The team found that samples from the 14 Covid patients who self-reported brain fog contained higher levels of a protein called S100β than those from Covid patients without this symptom or from people who have not had Covid.
This protein is made by cells in the brain and is not normally found in the blood, suggesting that these patients had a breakdown in the blood-brain barrier.
The research team then looked at 10 people who had recovered from Covid and 22 people with long-standing Covid, 11 of whom reported having brain fog. None had, at that time, received a Covid vaccine, or been hospitalized for Covid. These participants underwent an MRI scan. The results show that Long Covid patients with brain fog did indeed show signs of blood-brain barrier leakage, but not those who did not have this symptom or who had recovered.
One of the study's authors added that it is possible that people with a tighter blood-brain barrier are better protected against brain fog if they develop long-term Covid, explaining why the symptom did not appear in all patients.
Later research revealed that Long Covid patients with brain fog also showed signs of increased levels of proteins involved in clotting.
Incidentally, Matthew Campbell stated that the results were not a surprise, as disruptions to the proteins involved in clotting could go hand in hand with disruptions to the cells that line the blood vessels.
“The whole concept that many of these neurological conditions, including brain fog, could be treated by simply adjusting the integrity of the blood-brain barrier is really interesting“, he said.
Professor Paul Harrison of the University of Oxford, an author of previous work suggesting that blood clots in the brain could be a cause of brain fog in people with long-standing Covid, said the new study was important.
“It shows that abnormalities in the lining of blood vessels in the brain occur in people with post-Covid brain fog and adds to evidence that abnormal blood clotting also contributes“, he declared.
But the results came from patients who had Covid in the first wave, meaning it's plausible but unclear whether the same mechanisms occurred in others, such as those with later variants of the virus or who were vaccinated, a said the teacher.
Another professor, Claire Steves of King's College London, believes that the small number of participants involved could mean that the findings of group differences are due to chance, while the phenomenon called “brain fog” was not clearly defined and was self-reported by participants.
“Therefore, it is difficult to be sure how applicable these results are to the millions of people who have experienced this phenomenonshe said.
