A small study from the U.S . National Institutes of Health says the immune response caused by COVID-19 infection may damage the brain's blood vessels .
The reaction could lead to neurological problems known as long COVID .
In the study , researchers examined brain changes in nine people who died suddenly after being infected with SARS-CoV-2 , the virus that causes COVID-19 .
The results appeared last week in the publication Brain .
This causes inflammation and damage .
The results were similar to an earlier study done in 2020 .
This suggests the virus was not attacking the brain directly .
NIH scientist Avindra Nath is the senior researcher of the study .
He said , “We had previously shown blood vessel damage and inflammation in patients ’ brains at autopsy , but we didn't understand the cause of the damage .”
An autopsy is the examination of a dead body to find out the cause of death .
For the study , Dr . Nath and a team of researchers examined brain tissue from nine individuals between the ages of 24 and 73 .
The individuals were chosen because their scans showed signs of blood vessel damage in the brain .
The scans were then compared to those from 10 individuals in a control group .
The researchers found that antibodies produced to fight COVID-19 may mistakenly target cells that line the brain's blood vessels .
These cells , called endothelial cells , serve as barriers to keep harmful substances from reaching the brain .
Damage to the cells causes bleeding and blockage in some COVID-19 patients and increases the risk of stroke .
As in their earlier study , researchers found signs of leaky blood vessels .
This suggests that the links between endothelial cells in the blood-brain barrier were damaged .
Dr . Nath said that once the leaks happened , immune cells “may come to repair the damage , setting up inflammation ” in the brain .
Researchers also found changes in gene expression in areas with damage to the endothelial cells .
More than 300 genes showed decreased expression , while six genes showed increased expression .
The affected genes are connected to the brain's ability to deal with chemical imbalances in the body .
Together , these findings may provide information about the cause of neurological problems related to COVID-19 .
The findings may also be used to find new treatments to target the damaged links between the endothelial cells in the blood-brain barrier .
The study may also help with understanding and treating long-term neurological conditions after COVID-19 .
The conditions include headache , tiredness , loss of taste and smell , sleep problems , and forgetfulness known as “brain fog .”
If the nine patients in the study had survived , the researchers believe they would have likely developed long COVID .
“It is quite possible that this same immune response persists in long COVID patients ,” Dr . Nath said .
The findings , he added , are “very important ” to researchers seeking to find treatments for long COVID .