Post-corona brain fog could be due to a leak in the blood-brain barrier

According to a study by an Irish research group, the lingering symptoms experienced post-corona could be attributed to a disruption in the blood-brain barrier’s function. These symptoms often include ‘brain fog’, characterized by unusual fatigue, concentration difficulties, and memory problems.

The researchers from Trinity College in Ireland found in their study, published in Nature Neuroscience, that this disruption in the blood-brain barrier could explain these symptoms. The blood-brain barrier is the tight inner lining of the brain’s capillaries that prevents harmful substances from entering the brain tissue from the blood.

The research team collected blood samples from 76 hospital patients who were part of the first wave of the corona infection in spring 2020. They also had 25 controls from whom the corresponding samples had been taken before the pandemic. Of these, 14 patients who later experienced brain fog had a significantly increased amount of a marker in their blood that the blood-brain barrier would usually prevent from passing from the brain into the blood. Consequently, proteins that didn’t belong there had entered the brain from the blood.

Subsequent brain scans showed changes indicating a leakage in the blood-brain barrier in patients suffering from brain fog. Such changes were not evident in patients who did not experience brain fog. However, the patient group examined was small, and thus no concrete conclusions could be made.

Patients with brain fog had elevated markers of inflammatory reaction and blood clotting. Earlier studies have suggested that blood clots in cerebral blood vessels are linked to brain fog, a condition that is also associated with a failure in the blood-brain barrier. Excessive blood clotting is a characteristic of severe corona infection and the resultant inflammatory reaction.

Professor Matthew Campbell from Trinity College, who participated in the research, finds it exciting to consider that neurological problems linked to these symptoms could potentially be treated by simply adjusting the function of the blood-brain barrier. He also believes that the blood-brain barrier may play a significant role in other conditions such as chronic fatigue syndrome.

However, Professor Claire Steves from King’s College and Professor Riitta Lassila from the University of Helsinki caution against jumping to conclusions based on this study. They note that the sample size of the patient group was too small to be representative, and the observed differences could be coincidental. Lassila adds that the intriguing research result cannot be generalized, and currently, no methods exist to repair the blood-brain barrier.