Leaky Blood-Brain Barrier Linked to ‘Brain Fog’ in Long Covid Patients, Study Finds
For many individuals suffering from long Covid, “brain fog” is a frustrating symptom that affects their daily lives. Now, a new study suggests that this cognitive impairment may be caused by a leaky blood-brain barrier. The blood-brain barrier is responsible for regulating the entry and exit of substances into the brain, maintaining a delicate balance. When this balance is disrupted, it can lead to changes in neural function and wreak havoc, particularly in brain regions involved in memory consolidation and storage.
The research, conducted by Prof Matthew Campbell and his team at Trinity College Dublin, analyzed serum and plasma samples from 76 patients who were hospitalized with Covid in March or April 2020, as well as samples from 25 individuals before the pandemic. Among their findings, the researchers discovered that patients who self-reported brain fog had higher levels of a protein called S100β in their samples compared to those without this symptom or individuals who had not contracted Covid. S100β is normally produced by cells within the brain and is not typically found in the blood, suggesting a breakdown of the blood-brain barrier in these patients.
To further investigate this phenomenon, the researchers recruited 10 individuals who had recovered from Covid and 22 individuals with long Covid, 11 of whom reported experiencing brain fog. None of the participants had received a Covid vaccine or been hospitalized for the virus at that point. They underwent an MRI scan with the administration of a dye intravenously. The results revealed that long Covid patients with brain fog exhibited signs of a leaky blood-brain barrier, while those without this symptom or who had recovered did not show such signs.
Prof Campbell noted that individuals with a tighter blood-brain barrier might be better protected from brain fog if they develop long Covid, which could explain why the symptom does not arise in all patients. Additionally, further analysis in a subgroup of participants revealed increased levels of proteins involved in clotting in long Covid patients with brain fog. This suggests a potential link between disruptions to proteins involved in clotting and the breakdown of cells lining blood vessels, which could contribute to neurological conditions such as brain fog.
The implications of this study extend beyond long Covid patients. Prof Campbell believes that regulating the integrity of the blood-brain barrier could potentially treat various neurological conditions, including brain fog associated with other illnesses like ME. However, extensive research would be necessary to confirm this hypothesis.
The study has garnered attention from other experts in the field. Prof Paul Harrison from the University of Oxford, who previously suggested that blood clots in the brain may contribute to brain fog in long Covid patients, emphasized the importance of these findings. He stated that the study demonstrates abnormalities in the lining of blood vessels in the brain among individuals with post-Covid brain fog, further supporting the notion that abnormal blood clotting plays a role. However, he also noted that the study focused on patients from the first wave of Covid and that it remains unclear if the same mechanisms occur in individuals with later variants of the virus or those who have been vaccinated.
Prof Claire Steves from King’s College London raised some concerns about the study’s limitations. She pointed out that the small number of participants involved could introduce chance findings between groups, and that brain fog was self-reported by participants without a clear definition. Therefore, it is challenging to determine how applicable these results are to the millions of people who have experienced this phenomenon.
In conclusion, the study conducted by Prof Matthew Campbell and his team sheds light on the potential link between a leaky blood-brain barrier and brain fog in long Covid patients. The findings suggest that disruptions to the blood-brain barrier may contribute to cognitive impairment and neurological symptoms. While further research is needed to confirm these findings and explore potential treatments, this study provides valuable insights into the underlying mechanisms of brain fog and its impact on individuals with long Covid.
