DUBLIN (dpa-AFX) – Doctors have identified a physical cause of so-called brain fog in chronic Covid patients. Accordingly, the viral infection disrupts the blood supply system in the brain. Blood vessels are more permeable and less able to protect the brain from pathogens, toxins and other substances in the blood, according to a research team led by Matthew Campbell of Trinity College Dublin and Colin Doherty of St James's Hospital, Dublin (Ireland). Special issue “Nature Neuroscience”.
“For the first time, we've shown that leaky blood vessels in the human brain and an overactive immune system may be the main cause of the brain fog associated with chronic Covid,” Campbell explained. He and his colleagues began investigating a form of clouding of consciousness, also known as brain fog, in the early stages of the coronavirus pandemic in March and April 2020 by analyzing blood samples from 76 Covid patients at St James's Hospital. They found increased levels of the protein S100-beta, which is, among other things, a marker for a disturbed blood-brain barrier.
The boundary between the bloodstream and the central nervous system is called the blood-brain barrier. Thanks to special cells on the outside of the vessel wall, only certain substances can pass into the brain. It protects the brain from harmful substances and pathogens. When the blood-brain barrier is disrupted, substances enter the brain that would otherwise be protected.
Researchers have yet to elucidate the exact mechanism by which this system is weakened. They also visualized disruptions of the blood-brain barrier using imaging techniques. To do this, they used a special type of magnetic resonance imaging (MRI), dynamic contrast-based perfusion MRI. The flow of a contrast agent through a tissue is measured. Specialized MRI images show that in patients with brain fog, more contrast media enters the brain tissue outside the blood capillaries.
Campbell, Doherty and colleagues strongly believe that coronavirus is not the only viral infection that can damage the brain in this way. “The results may now change the way we understand and treat post-viral neurodegenerative diseases,” Doherty said. According to a report from Trinity College, in recent years it has been shown that in several neurological diseases – including multiple sclerosis (MS) – a viral infection can be a precipitating factor for the disease. The study authors are now investigating in detail what role the blood-brain barrier plays in this.
A corona infection can cause a series of health problems, for which the long term covid has been established. Symptoms include fatigue, dizziness and difficulty concentrating./fm/DP/jha
